Revert single-output postgresql, use cache breaker v3

The single-output postgresql (685d555) broke the eval because
downstream packages (haskell.nix libpq) depend on postgresql.lib
and postgresql.dev outputs which don't exist with outputs=["out"].

Revert to the standard 5-output postgresql with all the existing
fixes (jitSupport=false, perlSupport=false, fno-lto, etc) and add
a cache breaker v3 to force new derivation hashes. This ensures
the queue runner won't hit stale FailedPaths entries from previous
postgresql-musl orphaned store path failures.

Author: angerman

flake.nix

@@ -163,19 +163,12 @@
              outputChecks = {};
              separateDebugInfo = false;
              disallowedReferences = [];
-             # Merge all outputs into "out" to work around Determinate Nix
-             # orphaned store path bug on macOS (APFS). Multi-output derivations
-             # fail to register atomically in the Nix DB — the build completes
-             # but outputs remain orphaned (exist on disk, not valid in DB).
-             # sync-before-registering = true did not fix this. Single-output
-             # avoids the multi-output registration path entirely. Consumers
-             # (haskell.nix libpq) only need lib/ and bin/pg_config anyway.
-             outputs = [ "out" ];
-             # Replace the upstream postInstall which splits outputs and
-             # removes pg_config from $out. We need everything in $out.
-             postInstall = ''
-               make -C src/common pg_config.env
-               install -D src/common/pg_config.env "$out/nix-support/pg_config.env"
+             # Bump cache breaker v3: pre-built GCC on hydra with sandbox
+             # /usr/include, cleared all FailedPaths. Orphaned paths cleaned
+             # on all builders 2026-02-19.
+             preBuild = (old.preBuild or "") + ''
+               # cache breaker v3: 2026-02-19 all orphaned paths cleaned
+               true
              '';
            });
          });