Add debug output to postgresql postFixup for cycle investigation

Need to understand why remove-references-to isn't preventing the
dev↔lib reference cycle. Adding verbose output to show:
- Which files exist in the lib output
- Which files reference the dev hash before/after stripping

Author: angerman

flake.nix

@@ -178,11 +178,23 @@
              # through .la files and baked-in paths. Strip dev refs from lib
              # since lib is a runtime output that doesn't need dev at runtime.
              postFixup = (old.postFixup or "") + ''
+               echo "=== postFixup: stripping dev refs from lib ==="
+               echo "lib=$lib"
+               echo "dev=$dev"
+               echo "Files in lib:"
+               find "$lib" -type f | head -20
                # Delete .la files from lib — libtool archives embed absolute
                # paths to dev headers/libs and are unnecessary for runtime.
                find "$lib" -name '*.la' -delete
+               # Check which files in lib reference dev before stripping.
+               echo "Files in lib referencing dev hash:"
+               DEV_HASH=$(echo "$dev" | sed 's|/nix/store/||; s|-.*||')
+               grep -rl "$DEV_HASH" "$lib" 2>/dev/null || echo "  (none found)"
                # Strip any remaining references to $dev from the lib output.
                find "$lib" -type f -exec remove-references-to -t "$dev" {} +
+               echo "After stripping, files referencing dev hash:"
+               grep -rl "$DEV_HASH" "$lib" 2>/dev/null || echo "  (none found)"
+               echo "=== postFixup done ==="
              '';
            });
          });