Remove obsolete setting of CC and CXX to be clang and clang++ on macOS.
Remove obsolete setting of CC and CXX to be clang and clang++ on macOS.

MozillaSecurity/funfuzz,MozillaSecurity/funfuzz,nth10sd/funfuzz,nth10sd/funfuzz,nth10sd/funfuzz,MozillaSecurity/funfuzz