Module file extensions: pass a Sema through to the extension writer.

Module file extensions are likely to need access to
Sema/Preprocessor/ASTContext, and cannot get it through other
sources.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@255065 91177308-0d34-0410-b5e6-96231b3b80d8
5 files changed