By adding a default config.excludes pattern we can avoid individual
suppressions in subdirectories.
This matches LLVM's lit.cfg which also excludes a few other common non-test
filenames for consistency.
llvm-svn: 194814
Clear the FileManager's stat cache in between running
translation units, as the stat cache loaded from a pch
is only valid for one compiler invocation.
llvm-svn: 161047