Move stat metric to DiskInterface

Stat is not always used through Node::Stat, it is often used directly
through DiskInterface.  THe next patches will cause it to be called
even more often through DiskInterface, so move the metrics to
DiskInterface.

Author: colincross

src/disk_interface.cc

@@ -28,6 +28,7 @@
 #include <direct.h>  // _mkdir
 #endif
 
+#include "metrics.h"
 #include "util.h"
 
 namespace {
@@ -148,6 +149,7 @@ bool DiskInterface::MakeDirs(const string& path) {
 // RealDiskInterface -----------------------------------------------------------
 
 TimeStamp RealDiskInterface::Stat(const string& path, string* err) const {
+  METRIC_RECORD("node stat");
 #ifdef _WIN32
   // MSDN: "Naming Files, Paths, and Namespaces"
   // http://msdn.microsoft.com/en-us/library/windows/desktop/aa365247(v=vs.85).aspx

src/graph.cc

@@ -28,7 +28,6 @@
 #include "util.h"
 
 bool Node::Stat(DiskInterface* disk_interface, string* err) {
-  METRIC_RECORD("node stat");
   return (mtime_ = disk_interface->Stat(path_, err)) != -1;
 }