gl/vulkan: Fix static linking on macOS

gl/vulkan: Fix static linking on macOS

duplicate symbol '__invoke_on_main' in:
    /Library/Frameworks/GStreamer.framework/Versions/1.0/lib/libgstvulkan-1.0.a(cocoa_gstvkwindow_cocoa.m.o)
    /Library/Frameworks/GStreamer.framework/Versions/1.0/lib/libgstgl-1.0.a(cocoa_gstglwindow_cocoa.m.o)
ld: 1 duplicate symbol for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)

Also make the same change in iOS for consistency.

Continuation of https://gitlab.freedesktop.org/gstreamer/gst-plugins-bad/-/issues/1132

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/3242>