Add more ODR checking.

Add the basics for the ODRHash class, which will only process Decl's from
a whitelist, which currently only has AccessSpecDecl.  Different access
specifiers in merged classes can now be detected.

Differential Revision: https://reviews.llvm.org/D21675

llvm-svn: 295800
diff --git a/clang/lib/AST/CMakeLists.txt b/clang/lib/AST/CMakeLists.txt
index e28bd2e..2e98f52 100644
--- a/clang/lib/AST/CMakeLists.txt
+++ b/clang/lib/AST/CMakeLists.txt
@@ -40,6 +40,7 @@
   MicrosoftMangle.cpp
   NestedNameSpecifier.cpp
   NSAPI.cpp
+  ODRHash.cpp
   OpenMPClause.cpp
   ParentMap.cpp
   RawCommentList.cpp