v8: Hardfloat does not imply VFPv3, only VFPv2.

Raspberry Pi is an example.

BUG=v8:2393

Review URL: https://chromiumcodereview.appspot.com/11570061
Patch from Chi-Thanh Christopher Nguyen <nguyenchithanh@gmail.com>.

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@13232 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

This is a backport of v8/v8@44419ad089b729a1aab4a5f27c0833e2ce69d28b.

deps/v8/build/common.gypi

@@ -157,7 +157,7 @@
           [ 'v8_use_arm_eabi_hardfloat=="true"', {
             'defines': [
               'USE_EABI_HARDFLOAT=1',
-              'CAN_USE_VFP3_INSTRUCTIONS',
+              'CAN_USE_VFP2_INSTRUCTIONS',
             ],
             'target_conditions': [
               ['_toolset=="target"', {