Fix chromium integration issues in common.gypi
Fix chromium integration issues in common.gypi

Only define command settings when running in
nacl_standalone.  In the chromium tree chromium's
common.gypi takes care of these.

Review URL: https://codereview.chromium.org/1221403002

sbc100/native_client,sbc100/native_client,sbc100/native_client,sbc100/native_client,sbc100/native_client,sbc100/native_client