boinc_mac_iosurface.patch

* Required to support macOS 10.13+
* Our graphics app acts as a Mach RPC server that passes IOSurfaces to registered clients
* The BOINC screensaver acts as a Mach RPC server, rendering the IOSurface received
* Patching the BOINC build to include the required files (missing in non-Xcode build)
* Added MacIOSurfaceManager that sets up the Mach RPC server and controls the IOSurface textures
* Integrated the MacIOSurfaceManager into our WindowManager
* Note: we need to watch for upstream changes to macglutfix.m to retain compatibility

References:

* https://github.com/BOINC/boinc/pull/2149
* https://github.com/BOINC/boinc/blob/master/api/macglutfix.m
* https://developer.apple.com/library/archive/samplecode/MultiGPUIOSurface/Introduction/Intro.html