Implement GL_EXT_maximal_reconvergence #770

Job	Run time
emscripten	2m 8s
android (ON)	5m 22s
linux (clang, clang++, Debug)	7m 3s
android (OFF)	4m 39s
iOS	18m 7s
linux (clang, clang++, Release)	7m 19s
Linux Backcompat	17m 9s
linux (gcc, g++, Debug)	7m 32s
linux (gcc, g++, Release)	6m 17s
linux-asan (gcc, g++, Debug, -fsanitize=address)	9m 51s
macos (macos-12, clang, clang++, Debug)	11m 46s
windows (windows-2019, windows, Debug)	6m 42s
linux-asan (gcc, g++, Debug, -fsanitize=thread)	16m 50s
macos (macos-12, clang, clang++, Release)	12m 46s
windows (windows-2019, windows, Release)	6m 0s
macos (macos-12, gcc, g++, Debug)	8m 26s
macos (macos-12, gcc, g++, Release)	7m 27s
macos (macos-13, clang, clang++, Debug)	12m 51s
macos (macos-13, clang, clang++, Release)	15m 55s
macos (macos-13, gcc, g++, Debug)	15m 13s
macos (macos-13, gcc, g++, Release)	12m 25s
	3h 31m 48s

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