fix(deps): work around duplicate RPATHs in libgccjit from Nix

This is a horrible hack to work around macOS 15.4 no longer allowing the
use of shared libraries which have duplicate RPATHs. Annoying libgccjit
from Nix has two sets of duplicate RPATHs.

Hence the fix is to check the RPATHs of `libgccjit*.dylib`, remove any
duplicates, and also ensure there's no duplicates in CFLAGS, LDFLAGS, or
LIBRARY_PATHS which can cause libgccjit to output new compiled code with
duplicate RPATHs.

If needed, it will trigger sudo to modify the `libgccjit*.dylib` file
within the Nix store. It does create a `.bak` backup file, so you can
restore it if needed.

Author: jimeh

README.md

@@ -161,6 +161,7 @@ Options:
                                      Enable/disable keeping source folder for archive (default: disabled)
         --log-level LEVEL            Build script log level (default: info)
         --plan FILE                  Follow given plan file, instead of using given git ref/sha
+        --clean-macho-binary FILE    Tool to clean duplicate RPATHs from given Mach-O binary.
 ```
 
 Resulting applications are saved to the `builds` directory in a bzip2 compressed