only use gold-specific flags for the target linker

The host linker might not be gold if linux_use_gold_binary==0,
eg where we have a cross toolchain with gold and we want to use
that instead of third_party/gold/gold64.

Review URL: https://chromiumcodereview.appspot.com/19541006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@212823 0039d316-1c4b-4281-b951-d872f2087c98
1 file changed