Support Visual C++ PGO in Ninja generator

test/win/linker-flags/update_pgd.py

Index: test/win/linker-flags/update_pgd.py
===================================================================
--- test/win/linker-flags/update_pgd.py	(revision 0)
+++ test/win/linker-flags/update_pgd.py	(revision 0)
@@ -0,0 +1,35 @@
+#!/usr/bin/env python
+
+# Copyright (c) 2013 Google Inc. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+from optparse import OptionParser
+import glob
+import os
+import subprocess
+
+parser = OptionParser()
+parser.add_option('--exe', dest='exe')
+parser.add_option('--vcbindir', dest='vcbindir')
+parser.add_option('--pgd', dest='pgd')
+(options, args) = parser.parse_args()
+
+# Instrumented binaries fail to run unless the Visual C++'s bin dir is included
+# in the PATH environment variable.
+os.environ['PATH'] = os.environ['PATH'] + os.pathsep + options.vcbindir
+
+# Run Instrumented binary.  The profile will be recorded into *.pgc file.
+subprocess.call([options.exe])
+
+# Merge *.pgc files into a *.pgd (Profile-Guided Database) file.
+subprocess.call(['pgomgr', '/merge', options.pgd])
+
+# *.pgc files are no longer necessary. Clear all of them.
+pgd_file = os.path.abspath(options.pgd)
+pgd_dir = os.path.dirname(pgd_file)
+(pgd_basename, _) = os.path.splitext(os.path.basename(pgd_file))
+pgc_filepattern = os.path.join(pgd_dir, '%s!*.pgc' % pgd_basename)
+pgc_files= glob.glob(pgc_filepattern)
+for pgc_file in pgc_files:
+  os.unlink(pgc_file)