[WIP] Support hybrid LTO/non-LTO rlibs. #4515

Job	Run time
test_llvm	44s
rustfmt	14s
todo_check	24s
test (ubuntu-latest, riscv64gc-unknown-linux-gnu, gcc-riscv64-linux-gnu qemu-user)	2m 20s
dist (ubuntu-24.04-arm, aarch64-unknown-linux-gnu)	1m 41s
test (ubuntu-latest, x86_64-unknown-linux-gnu)	2m 3s
dist (macos-15-intel, x86_64-apple-darwin)	4m 10s
test (windows-latest, x86_64-pc-windows-msvc)	3m 46s
bench	2m 7s
dist (ubuntu-22.04, x86_64-unknown-linux-gnu)	1m 53s
dist (macos-latest, aarch64-apple-darwin)	2m 16s
test (ubuntu-24.04-arm, aarch64-unknown-linux-gnu)	1m 47s
test (ubuntu-latest, s390x-unknown-linux-gnu, gcc-s390x-linux-gnu qemu-user)	2m 21s
test (windows-latest, x86_64-pc-windows-gnu)	4m 12s
dist (windows-latest, x86_64-pc-windows-gnu)	3m 58s
test (macos-15-intel, x86_64-apple-darwin)	5m 38s
test (macos-latest, aarch64-apple-darwin)	2m 40s
dist (windows-latest, x86_64-pc-windows-msvc)	4m 40s
release	0s
	46m 54s

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