StdLib: Added BaseStackLib for ARM architectures

StdLib: Added BaseStackLib for ARM architectures

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Olivier Martin <Olivier.Martin@arm.com>
Reviewed-by: Ronald Cron <Ronald.Cron@arm.com>
Reviewed-by: Jaben Carsey <jaben.carsey@intel.com>
Reviewed-by: Daryl McDaniel <edk2-lists@mc2research.org>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@18115 6f19259b-4bc3-4df7-8a09-765794883524