LangOptions, rather than making distinct copies of
LangOptions. Granted, LangOptions doesn't actually get modified, but
this will eventually make it easier to construct ASTContext and
Preprocessor before we know all of the LangOptions.




git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@138959 91177308-0d34-0410-b5e6-96231b3b80d8