Unbreak mongo build

Summary: Unbreak build for mongo.  later, we'll have to figure out if there is a platform independent way to implement ROCKSDB_WARNING

Test Plan: build

Reviewers: igor, sdong

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D42369

include/rocksdb/utilities/convenience.h

@@ -7,6 +7,7 @@
 
 #include "utilities/pragma_error.h"
 
-ROCKSDB_WARNING("This file was moved to rocksdb/convenience.h")
+// TODO(agiardullo):  need to figure out how to make this portable
+// ROCKSDB_WARNING("This file was moved to rocksdb/convenience.h")
 
 #include "rocksdb/convenience.h"