cocoa: Make sure GL context destruction happens on the main thread. #2

Job	Run time
Create test plan	5s
level1 / Haiku	1m 48s
level2 / Android (Android.mk)	2m 15s
level2 / Windows (msys2, clang64)	5m 53s
level2 / GDK (MSVC, x64)	2m 45s
level2 / Sony PlayStation Vita (GLES w/ PVR_PSP2)	3m 15s
level2 / Windows (msys2, ucrt64)	8m 20s
level2 / Windows (MSVC, ARM64)	3m 4s
level2 / Sony PlayStation 2	4m 45s
level2 / Windows (msys2, clang32)	6m 41s
level2 / iOS (CMake & xcode)	2m 9s
level2 / Sony PlayStation Portable	3m 37s
level2 / Android (CMake, lean)	6m 5s
level2 / Windows (MSVC, x86)	4m 56s
level2 / tvOS (CMake & xcode)	2m 20s
level2 / Windows (MSVC, clang-cl x64)	7m 45s
level2 / PowerPC64	1m 48s
level2 / FreeBSD	2m 50s
level2 / Ubuntu 20.04	3m 59s
level2 / Windows (msys2, mingw32)	8m 38s
level2 / Sony PlayStation Vita (GLES w/ pib)	3m 11s
level2 / Nintendo 3DS	1m 54s
level2 / Windows (MSVC, x64)	5m 7s
level2 / MacOS (Framework) (arm64)	2m 29s
level2 / LoongArch64	2m 53s
level2 / Emscripten	9m 9s
level2 / Ubuntu 20.04 (Intel Compiler)	4m 32s
level2 / Windows (MSVC, ARM)	4m 21s
level2 / MacOS (Framework) (x64)	5m 54s
level2 / Windows (msys2, mingw64)	8m 16s
level2 / MacOS (GNU prefix)	6m 20s
level2 / RISC OS	1m 21s
level2 / Ubuntu 20.04 (Intel oneAPI)	6m 23s
level2 / Ubuntu 22.04	4m 14s
level2 / NetBSD	2m 37s
level2 / Windows (MSVC, clang-cl x86)	5m 34s
level2 / Android (Gradle)	2m 17s
level2 / Android (CMake)	3m 58s
	2h 43m 28s

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