Get rid of a "using namespace"

Summary: Its better to be explicit, and icc doesn't like it.

Reviewed By: ricklavoie

Differential Revision: D10163088

fbshipit-source-id: b4dc44973759e5e902ac91ba7d15ca0abf73959e

hphp/runtime/vm/jit/mcgen-translate.cpp

@@ -160,8 +160,9 @@ createCallGraph(jit::hash_map<hfsort::TargetId, FuncId>& funcID) {
   ProfData::Session pds;
   assertx(profData() != nullptr);
 
-  using namespace hfsort;
-  TargetGraph cg;
+  using hfsort::TargetId;
+
+  hfsort::TargetGraph cg;
   jit::hash_map<FuncId, TargetId> targetID;
   auto pd = profData();