vbutil: accept amd64 as a valid alias for x86

The rest of the chromiumos build system uses amd64 as the
architecture name for 64bit x86.  This adds support for this
name to vbutil.

BUG=chromium-os:21284
TEST=vbutil --arch amd64 should not return unknown architecture

Change-Id: I37531591a7a31486f6447ae611d54569d1ea59d5
Reviewed-on: http://gerrit.chromium.org/gerrit/9959
Tested-by: Sonny Rao <sonnyrao@chromium.org>
Reviewed-by: Randall Spangler <rspangler@chromium.org>
1 file changed