libnbd: remove unused fuse

[BatteredBunny]

libnbd uses fuse3 only since https://gitlab.com/nbdkit/libnbd/-/commit/c74c7d7f (1.8.0)

Related #526161

Things done

• Built on platform:
  • x86_64-linux
  • aarch64-linux
  • aarch64-darwin
• Tested, as applicable:
  • NixOS tests in nixos/tests.
  • Package tests at passthru.tests.
  • Tests in lib/tests or pkgs/test for functions and "core" functionality.
• Ran nixpkgs-review on this PR. See nixpkgs-review usage.
• Tested basic functionality of all binary files, usually in ./result/bin/.
• Nixpkgs Release Notes
  • Package update: when the change is major or breaking.
• NixOS Release Notes
  • Module addition: when adding a new NixOS module.
  • Module update: when the change is significant.
• Fits CONTRIBUTING.md, pkgs/README.md, maintainers/README.md and other READMEs.
• Follows the automation/AI policy.

[BatteredBunny]

nixpkgs-review result

Generated using nixpkgs-review.

Command: nixpkgs-review pr 543809
Commit: 7f9d0310c08c549c750f16994e8221df3b81981a

---

x86_64-linux

❌ 4 packages failed to build:

• ceph (ceph-client, ceph-dev, libceph)
• ceph-csi
• qemu_full
• sambaFull (samba4Full)

✅ 12 packages built:

• fio
• kdiskmark
• libnbd
• nbdkit
• ocamlPackages.nbd
• ocamlPackages_latest.nbd
• poke
• python313Packages.libnbd
• python314Packages.libnbd
• virt-v2v
• virtnbdbackup
• xfstests

---

ceph

make[2]: *** Waiting for unfinished jobs....
In file included from /nix/store/0axpqqmj1rcanmm2i8vzpd8xxwkmq2jf-gcc-15.2.0/include/c++/15.2.0/set:64,
                 from /build/ceph-20.2.2.tar.gz-patched/src/include/encoding.h:18,
                 from /build/ceph-20.2.2.tar.gz-patched/src/include/uuid.h:9,
                 from /build/ceph-20.2.2.tar.gz-patched/src/include/types.h:21,
                 from /build/ceph-20.2.2.tar.gz-patched/src/common/ceph_crypto.h:10,
                 from /build/ceph-20.2.2.tar.gz-patched/src/rgw/rgw_rest_s3.cc:11:
In member function 'std::_Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::_Base_ptr std::_Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::_M_begin() const [with _Key = std::__cxx11::basic_string<char>; _Val = std::pair<const std::__cxx11::basic_string<char>, rgw_sync_policy_group>; _KeyOfValue = std::_Select1st<std::pair<const std::__cxx11::basic_string<char>, rgw_sync_policy_group> >; _Compare = std::less<std::__cxx11::basic_string<char> >; _Alloc = std::allocator<std::pair<const std::__cxx11::basic_string<char>, rgw_sync_policy_group> >]',
    inlined from 'std::_Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::iterator std::_Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::find(const _Key&) [with _Key = std::__cxx11::basic_string<char>; _Val = std::pair<const std::__cxx11::basic_string<char>, rgw_sync_policy_group>; _KeyOfValue = std::_Select1st<std::pair<const std::__cxx11::basic_string<char>, rgw_sync_policy_group> >; _Compare = std::less<std::__cxx11::basic_string<char> >; _Alloc = std::allocator<std::pair<const std::__cxx11::basic_string<char>, rgw_sync_policy_group> >]' at /nix/store/0axpqqmj1rcanmm2i8vzpd8xxwkmq2jf-gcc-15.2.0/include/c++/15.2.0/bits/stl_tree.h:3152:16,
    inlined from 'std::map<_Key, _Tp, _Compare, _Alloc>::iterator std::map<_Key, _Tp, _Compare, _Alloc>::find(const key_type&) [with _Key = std::__cxx11::basic_string<char>; _Tp = rgw_sync_policy_group; _Compare = std::less<std::__cxx11::basic_string<char> >; _Alloc = std::allocator<std::pair<const std::__cxx11::basic_string<char>, rgw_sync_policy_group> >]' at /nix/store/0axpqqmj1rcanmm2i8vzpd8xxwkmq2jf-gcc-15.2.0/include/c++/15.2.0/bits/stl_map.h:1260:25,
    inlined from 'virtual void RGWGetBucketReplication_ObjStore_S3::send_response_data()' at /build/ceph-20.2.2.tar.gz-patched/src/rgw/rgw_rest_s3.cc:1560:36:
/nix/store/0axpqqmj1rcanmm2i8vzpd8xxwkmq2jf-gcc-15.2.0/include/c++/15.2.0/bits/stl_tree.h:1378:40: warning: '*(const std::_Rb_tree<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::pair<const std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, rgw_sync_policy_group>, std::_Select1st<std::pair<const std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, rgw_sync_policy_group> >, std::less<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > >, std::allocator<std::pair<const std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, rgw_sync_policy_group> > >*)((char*)&policy + offsetof(std::optional<rgw_sync_policy_info>,std::optional<rgw_sync_policy_info>::<unnamed>.std::_Optional_base<rgw_sync_policy_info, false, false>::_M_payload.std::_Optional_payload<rgw_sync_policy_info, false, false, false>::<unnamed>.std::_Optional_payload<rgw_sync_policy_info, true, false, false>::<unnamed>.std::_Optional_payload_base<rgw_sync_policy_info>::_M_payload)).std::_Rb_tree<std::__cxx11::basic_string<char>, std::pair<const std::__cxx11::basic_string<char>, rgw_sync_policy_group>, std::_Select1st<std::pair<const std::__cxx11::basic_string<char>, rgw_sync_policy_group> >, std::less<std::__cxx11::basic_string<char> >, std::allocator<std::pair<const std::__cxx11::basic_string<char>, rgw_sync_policy_group> > >::_M_impl.std::_Rb_tree<std::__cxx11::basic_string<char>, std::pair<const std::__cxx11::basic_string<char>, rgw_sync_policy_group>, std::_Select1st<std::pair<const std::__cxx11::basic_string<char>, rgw_sync_policy_group> >, std::less<std::__cxx11::basic_string<char> >, std::allocator<std::pair<const std::__cxx11::basic_string<char>, rgw_sync_policy_group> > >::_Rb_tree_impl<std::less<std::__cxx11::basic_string<char> >, true>::std::_Rb_tree_header.std::_Rb_tree_header::_M_header.std::_Rb_tree_node_base::_M_parent' may be used uninitialized [8;;https://gcc.gnu.org/onlinedocs/gcc-15.2.0/gcc/Warning-Options.html#index-Wmaybe-uninitialized�-Wmaybe-uninitialized8;;�]
 1378 |       { return this->_M_impl._M_header._M_parent; }
      |                                        ^~~~~~~~~
/build/ceph-20.2.2.tar.gz-patched/src/rgw/rgw_rest_s3.cc: In member function 'virtual void RGWGetBucketReplication_ObjStore_S3::send_response_data()':
/build/ceph-20.2.2.tar.gz-patched/src/rgw/rgw_rest_s3.cc:1558:10: note: 'policy' declared here
 1558 |     auto policy = s->bucket->get_info().sync_policy;
      |          ^~~~~~
make[1]: *** [CMakeFiles/Makefile2:10889: src/rgw/CMakeFiles/rgw_common.dir/all] Error 2
make: *** [Makefile:146: all] Error 2

[BatteredBunny]

Ceph failure unrelated to this PR's changes. #542206

[SuperSandroBot]

❌ nixpkgs-review result

Generated using nixpkgs-review-gha (71d8654)

Command: nixpkgs-review pr 543809
Commit: 7f9d0310c08c549c750f16994e8221df3b81981a (subsequent changes)
Merge: c7b5baf134ac8339399dfcec8983e9681502387f

Logs: https://github.com/SuperSandro2000/nixpkgs-review-gha/actions/runs/29737057503/attempts/1

---

x86_64-linux

❌ 4 packages failed to build:

• ceph (ceph-client, ceph-dev, libceph)
• ceph-csi
• qemu_full
• sambaFull (samba4Full)

✅ 12 packages built:

• fio
• kdiskmark
• libnbd
• nbdkit
• ocamlPackages.nbd
• ocamlPackages_latest.nbd
• poke
• python313Packages.libnbd
• python314Packages.libnbd
• virt-v2v
• virtnbdbackup
• xfstests

---

aarch64-linux

❌ 3 packages failed to build:

• ceph (ceph-client, ceph-dev, libceph)
• ceph-csi
• qemu_full

✅ 11 packages built:

• fio
• kdiskmark
• libnbd
• nbdkit
• ocamlPackages.nbd
• ocamlPackages_latest.nbd
• poke
• python313Packages.libnbd
• python314Packages.libnbd
• virtnbdbackup
• xfstests