llvm-project

cd5ed7ca - [libc++] Make CC and CXX environment variables mandatory in run-buildbot (#166875)

[libc++] Make CC and CXX environment variables mandatory in run-buildbot (#166875) Previously, the bootstrapping-build job defined in run-buildbot required the CC and CXX environment variables to be defined even though run-buildbot documents these environment variables as being optional. It also relied on ccache being available. Refactor run-buildbot to make CC and CXX mandatory, and refactor various places in the CI where we called run-buildbot without setting CC and CXX. After this patch, all places that use run-buildbot are setting CC and CXX before calling the script, which makes it easier to track what compiler is used where. This also allows simplifying run-buildbot itself. Finally, this patch makes ccache optional for running the bootstrapping build.