[libclang/AST] Index references of protocols in "@protocol(...)" syntax.

To do that, keep track of the location of the protocol id in the ObjCProtocolExpr
AST node.

rdar://11190837

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@156890 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Serialization/ASTWriterStmt.cpp b/lib/Serialization/ASTWriterStmt.cpp
index 4f25e70..9921d6e 100644
--- a/lib/Serialization/ASTWriterStmt.cpp
+++ b/lib/Serialization/ASTWriterStmt.cpp
@@ -837,6 +837,7 @@
   VisitExpr(E);
   Writer.AddDeclRef(E->getProtocol(), Record);
   Writer.AddSourceLocation(E->getAtLoc(), Record);
+  Writer.AddSourceLocation(E->ProtoLoc, Record);
   Writer.AddSourceLocation(E->getRParenLoc(), Record);
   Code = serialization::EXPR_OBJC_PROTOCOL_EXPR;
 }