Fix xcode tool chain assembly issue. 

Contributed-under: TianoCore Contribution Agrement 1.0
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
signed-off-by: Andrew Fish <afish@apple.com>



git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@14078 6f19259b-4bc3-4df7-8a09-765794883524