compiler-rt is optional. We often get email from users with compiler-rt
build errors who don't actually need compiler-rt. Marking it optional
should help them avoid those potential problems.
While I'm here, update a reference to the build directory and remove an
obsolete reference to llvm-gcc. Nobody today is under the impression
that Clang depends on GCC.
llvm-svn: 265963
88cbe5a1cc
