Add "/usr/local/lib/libvulkan.dylib" as a path checked when loading Vulkan on MacOS

[ItchyTrack]

I was having a issue where SDL was not loading with the error of SDL could not create window! SDL_Error: Failed to load Vulkan Portability library. I am also using volk and I saw volk was loading Vulkan from "/usr/local/lib/libvulkan.dylib". SDL does not check this path and so I added it as the last path checked.

This fixed my issues and based on the comments in volk // modern versions of macOS don't search /usr/local/lib automatically contrary to what man dlopen says this may not have been a problem in the past.

Old:

const char *defaultPaths[] = {
    "@executable_path/../Frameworks/libMoltenVK.dylib",
    "vulkan.framework/vulkan",
    "libvulkan.1.dylib",
    "libvulkan.dylib",
    "MoltenVK.framework/MoltenVK",
    "libMoltenVK.dylib"
};

New:

const char *defaultPaths[] = {
    "@executable_path/../Frameworks/libMoltenVK.dylib",
    "vulkan.framework/vulkan",
    "libvulkan.1.dylib",
    "libvulkan.dylib",
    "MoltenVK.framework/MoltenVK",
    "libMoltenVK.dylib",
    "/usr/local/lib/libvulkan.dylib"
};