Add a C++11 and C2x spelling for the objc_bridge_related attribute in the clang vendor namespace.

This attribute has custom parsing rules that previously prevented it from being supported with square bracket notation.

llvm-svn: 326038
diff --git a/clang/lib/Parse/ParseDecl.cpp b/clang/lib/Parse/ParseDecl.cpp
index ade822b..d79ca8a 100644
--- a/clang/lib/Parse/ParseDecl.cpp
+++ b/clang/lib/Parse/ParseDecl.cpp
@@ -416,6 +416,10 @@
     ParseAvailabilityAttribute(*AttrName, AttrNameLoc, Attrs, EndLoc, ScopeName,
                                ScopeLoc, Syntax);
     break;
+  case AttributeList::AT_ObjCBridgeRelated:
+    ParseObjCBridgeRelatedAttribute(*AttrName, AttrNameLoc, Attrs, EndLoc,
+                                    ScopeName, ScopeLoc, Syntax);
+    break;
   }
   return Attrs.getList() ? Attrs.getList()->getNumArgs() : 0;
 }