Basic/Diagnostics: Split out the default warning "no-Werror" and
"show-in-system-header" bits, which is part of teasing them apart from the
diagnostic mapping kind.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@140742 91177308-0d34-0410-b5e6-96231b3b80d8
10 files changed