add gyp define to enable svn version check. defaults to off so tests built outside of svn will build/run with a warning but not error.

BUG=356
TESTED=set GYP_DEFINES=target_arch=ia32 libyuv_disable_jpeg=1 libyuv_enable_svn=1
R=thorcarpenter@google.com

Review URL: https://webrtc-codereview.appspot.com/17329004

git-svn-id: http://libyuv.googlecode.com/svn/trunk@1075 16f28f9a-4ce2-e073-06de-1de4eb20be90

README.chromium

@@ -1,6 +1,6 @@
 Name: libyuv
 URL: http://code.google.com/p/libyuv/
-Version: 1074
+Version: 1075
 License: BSD
 License File: LICENSE
 

include/libyuv/version.h

@@ -11,6 +11,6 @@
 #ifndef INCLUDE_LIBYUV_VERSION_H_  // NOLINT
 #define INCLUDE_LIBYUV_VERSION_H_
 
-#define LIBYUV_VERSION 1074
+#define LIBYUV_VERSION 1075
 
 #endif  // INCLUDE_LIBYUV_VERSION_H_  NOLINT

libyuv_test.gyp

@@ -9,6 +9,7 @@
 {
   'variables': {
     'libyuv_disable_jpeg%': 0,
+    'libyuv_enable_svn%': 0,
   },
   'targets': [
     {
@@ -21,7 +22,6 @@
         'testing/gtest.gyp:gtest_main',
       ],
       'defines': [
-        'LIBYUV_SVNREVISION="<!(svnversion -n)"',
         # Enable the following 3 macros to turn off assembly for specified CPU.
         # 'LIBYUV_DISABLE_X86',
         # 'LIBYUV_DISABLE_NEON',
@@ -49,6 +49,11 @@
         'unit_test/version_test.cc',
       ],
       'conditions': [
+        [ 'libyuv_enable_svn == 1', {
+          'defines': [
+            'LIBYUV_SVNREVISION="<!(svnversion -n)"',
+          ],
+        }],
         ['OS=="linux"', {
           'cflags': [
             '-fexceptions',

unit_test/version_test.cc

@@ -36,6 +36,8 @@ TEST_F(libyuvTest, TestVersion) {
   if (LIBYUV_VERSION != svn_revision) {
     printf("WARNING - Versions do not match.\n");
   }
+#else
+  printf("WARNING - SVN Version unavailable.  Test not run.\n");
 #endif
 }