Adding msvs2013 support to scons.

Rather than absorb the risk of a scons upgrade at this moment,
patching scons to support msvs2013, so that we can use our new 32-bit trybots.

BUG=http://code.google.com/p/chromium/issues/detail?id=357183
TEST=local on bot
R=jvoung@chromium.org

Review URL: https://codereview.chromium.org/218403011

git-svn-id: svn://svn.chromium.org/native_client/trunk/src/third_party/scons-2.0.1@12970 fcba33aa-ac0c-11dd-b9e7-8d5594d729c2
diff --git a/README.nacl b/README.nacl
index e917673..5fd35e9 100644
--- a/README.nacl
+++ b/README.nacl
@@ -19,3 +19,6 @@
 Applied workaround from: http://scons.tigris.org/issues/show_bug.cgi?id=2449
 NOTE: Both python and SCons are NOT planning to fix this, so we will need this
 fix even when upgrading to newer versions of scons or python.
+
+Added Visual Studio 2013 support (by registry detection only) to
+engine/SCons/Tools/MSCommon/vc.py
diff --git a/engine/SCons/Tool/MSCommon/vc.py b/engine/SCons/Tool/MSCommon/vc.py
index 0aeb3e7..2390ba6 100644
--- a/engine/SCons/Tool/MSCommon/vc.py
+++ b/engine/SCons/Tool/MSCommon/vc.py
@@ -128,9 +128,11 @@
 
     return (host, target,req_target_platform)
 
-_VCVER = ["10.0", "9.0", "9.0Exp","8.0", "8.0Exp","7.1", "7.0", "6.0"]
+_VCVER = ["12.0", "10.0", "9.0", "9.0Exp","8.0", "8.0Exp","7.1", "7.0", "6.0"]
 
 _VCVER_TO_PRODUCT_DIR = {
+        '12.0': [
+            r'Microsoft\VisualStudio\12.0\Setup\VC\ProductDir'],
         '10.0': [
             r'Microsoft\VisualStudio\10.0\Setup\VC\ProductDir'],
         '9.0': [