Do not use register pair in a parallel move.

The ParallelMoveResolver does not work with pairs. Instead,
decompose the pair into two individual moves.

Change-Id: Ie9d3f0b078cef8dc20640c98b20bb20cc4971a7f
diff --git a/compiler/optimizing/code_generator_x86.cc b/compiler/optimizing/code_generator_x86.cc
index 1a0df44..bdd0979 100644
--- a/compiler/optimizing/code_generator_x86.cc
+++ b/compiler/optimizing/code_generator_x86.cc
@@ -3363,7 +3363,7 @@
       __ movl(Address(ESP, destination.GetStackIndex()), imm);
     }
   } else {
-    LOG(FATAL) << "Unimplemented";
+    LOG(FATAL) << "Unimplemented move: " << destination << " <- " << source;
   }
 }