[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

llvm-svn: 156890
diff --git a/clang/lib/Serialization/ASTReaderStmt.cpp b/clang/lib/Serialization/ASTReaderStmt.cpp
index 9eda98c..965b4d1 100644
--- a/clang/lib/Serialization/ASTReaderStmt.cpp
+++ b/clang/lib/Serialization/ASTReaderStmt.cpp
@@ -873,6 +873,7 @@
   VisitExpr(E);
   E->setProtocol(ReadDeclAs<ObjCProtocolDecl>(Record, Idx));
   E->setAtLoc(ReadSourceLocation(Record, Idx));
+  E->ProtoLoc = ReadSourceLocation(Record, Idx);
   E->setRParenLoc(ReadSourceLocation(Record, Idx));
 }