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.

llvm-svn: 255065
diff --git a/clang/lib/Frontend/TestModuleFileExtension.h b/clang/lib/Frontend/TestModuleFileExtension.h
index 2a72454..41f3ca9 100644
--- a/clang/lib/Frontend/TestModuleFileExtension.h
+++ b/clang/lib/Frontend/TestModuleFileExtension.h
@@ -30,7 +30,8 @@
     Writer(ModuleFileExtension *Ext) : ModuleFileExtensionWriter(Ext) { }
     ~Writer() override;
 
-    void writeExtensionContents(llvm::BitstreamWriter &Stream) override;
+    void writeExtensionContents(Sema &SemaRef,
+                                llvm::BitstreamWriter &Stream) override;
   };
 
   class Reader : public ModuleFileExtensionReader {