osxbundle: fix Vulkan dylib install name

[al3xtjames]

MoltenVK from Homebrew hardcodes the install name of libMoltenVK.dylib to point to the Homebrew prefix:

$ otool -l mpv.app/Contents/Frameworks/libMoltenVK.dylib | grep -A2 LC_ID_DYLIB
          cmd LC_ID_DYLIB
      cmdsize 72
         name /usr/local/opt/molten-vk/lib/libMoltenVK.dylib (offset 24)

Update dylib_unhell to update the install name in libMoltenVK.dylib to avoid depending on the Homebrew prefix.

[github-actions]

Download the artifacts for this pull request:

Windows

• mpv-i686-w64-mingw32
• mpv-x86_64-w64-mingw32
• mpv-x86_64-windows-msvc

macOS

• mpv-macos-13-intel
• mpv-macos-14-arm
• mpv-macos-15-arm

[al3xtjames]

After doing some additional testing I don't think is necessary - MoltenVK successfully loads even if the path specified by the install name doesn't exist. I was trying to fix the case where /usr/local/bin/mpv is a symlink to /Applications/mpv.app/Contents/MacOS/mpv. Trying to run /usr/local/bin/mpv --gpu-api=vulkan -v shows that Vulkan initialization fails with VK_ERROR_INCOMPATIBLE_DRIVER, but /Applications/mpv.app/Contents/MacOS/mpv --gpu-api=vulkan -v works fine. Changing the install name of libMoltenVK.dylib doesn't fix it.

[Akemi]

there is nothing broken i would say. the vulkan loader dynamically searchs in certain paths for the drivers and loaders:

• https://github.com/KhronosGroup/Vulkan-Loader/blob/main/docs/LoaderDriverInterface.md#example-macos-driver-search-path
• https://github.com/KhronosGroup/Vulkan-Loader/blob/main/docs/LoaderLayerInterface.md#macos-layer-discovery
• https://github.com/mpv-player/mpv/blob/master/TOOLS/dylib_unhell.py#L217-L228

the Contents/Resources/vulkan/icd.d/MoltenVK_icd.json (in the bundle), which we copy from found vulkan/moltenvk installation, is modified to point to the corresponding libMoltenVK.dylib ("library_path": "../../../Frameworks/libMoltenVK.dylib",). that dylib is also copied to the bundle.

just means the driver/loader is properly found within your bundle (relative path), but not found on your system because it's not installed to any of the standard search paths of vulkan/moltenvk.

[al3xtjames]

Yeah, I came to the same conclusion after a while. I ended up working around it by replacing the symlink with a wrapper script that invokes /Applications/mpv.app/Contents/MacOS/mpv.