Reintroduce the ASTConsumer/ASTUnit fix from r110610, it has nothing to do with the breakage.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@110840 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/AST/ASTConsumer.cpp b/lib/AST/ASTConsumer.cpp
index f37cbde..04a084a 100644
--- a/lib/AST/ASTConsumer.cpp
+++ b/lib/AST/ASTConsumer.cpp
@@ -17,3 +17,6 @@
 
 void ASTConsumer::HandleTopLevelDecl(DeclGroupRef D) {}
 
+void ASTConsumer::HandleInterestingDecl(DeclGroupRef D) {
+  HandleTopLevelDecl(D);
+}