[RFC] Proposing libcxx-config.py: a configuration tool for building and using libc++

Configuring a compiler to target or build libc++ is tricky. It often

requires suppressing and rebuilding large parts of the CC1 compiler
invocation. Doing this manually can be prohibitive, even for experienced

Yes this was definitely hard for me also at the first time especially
when bootstrapping clang on some old distros like either centos5 or
debian6. +1 for me purposing new automated script instead of manually
passing cmake args and configuring llvm folder tree layout.