clang: Add support for a CC_PRINT_HEADERS environment variable, which mirrors
CC_PRINT_OPTIONS and can be used to get some out-of-band information on header
usage from a build.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@124751 91177308-0d34-0410-b5e6-96231b3b80d8
4 files changed