CMake

Add ability to build with Clang on macOS #2244

Job	Run time
run_tests_clang (Release)	38m 47s
run_tests_gcc (Release)	29m 8s
run_tests_macos_clang (Release)	5m 27s
run_tests_clang (Debug)	3h 31m 59s
run_tests_gcc (Debug)	58m 5s
run_tests_macos_clang (Debug)	5m 33s
run_tests_clang (Debug, ADDRESS)	48m 23s
run_tests_gcc (Debug, ADDRESS)	52m 47s
run_tests_macos_clang (Debug, ADDRESS)	5m 7s
run_tests_clang (Debug, UB)	1h 7m 58s
run_tests_gcc (Debug, UB)	42m 16s
run_tests_macos_clang (Debug, UB)	4m 35s
	9h 30m 5s

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