Move MachineTraceMetrics.h into include/llvm/CodeGen.

Let targets use it.

llvm-svn: 172688
diff --git a/llvm/lib/CodeGen/MachineTraceMetrics.cpp b/llvm/lib/CodeGen/MachineTraceMetrics.cpp
index 685ccab..f77a7b1 100644
--- a/llvm/lib/CodeGen/MachineTraceMetrics.cpp
+++ b/llvm/lib/CodeGen/MachineTraceMetrics.cpp
@@ -8,7 +8,7 @@
 //===----------------------------------------------------------------------===//
 
 #define DEBUG_TYPE "machine-trace-metrics"
-#include "MachineTraceMetrics.h"
+#include "llvm/CodeGen/MachineTraceMetrics.h"
 #include "llvm/ADT/PostOrderIterator.h"
 #include "llvm/ADT/SparseSet.h"
 #include "llvm/CodeGen/MachineBasicBlock.h"