Define CAN_USE_ARMV7_INSTRUCTIONS if armv7 gyp flag is set.

R=jkummerow@chromium.org

Review URL: https://chromiumcodereview.appspot.com/11274008

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@12807 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

build/common.gypi

@@ -134,6 +134,11 @@
           'V8_TARGET_ARCH_ARM',
         ],
         'conditions': [
+          ['armv7==1', {
+            'defines': [
+              'CAN_USE_ARMV7_INSTRUCTIONS=1',
+            ],
+          }],
           [ 'v8_can_use_unaligned_accesses=="true"', {
             'defines': [
               'CAN_USE_UNALIGNED_ACCESSES=1',