When we load the first module, make sure that we wire up the ASTConsumer to the newly-created ASTReader. This makes sure that CodeGen sees the declarations it is interested in

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@139824 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Serialization/ASTReader.cpp b/lib/Serialization/ASTReader.cpp
index 30c4429..e4f9fa6 100644
--- a/lib/Serialization/ASTReader.cpp
+++ b/lib/Serialization/ASTReader.cpp
@@ -4092,6 +4092,7 @@
     // passing to the consumer.
     GetDecl(ExternalDefinitions[I]);
   }
+  ExternalDefinitions.clear();
 
   PassInterestingDeclsToConsumer();
 }