BaseTools AARCH64: build XIP modules with strict alignment

BaseTools AARCH64: build XIP modules with strict alignment

GCC for AARCH64 recognizes byte swapping load and store sequences
and may replace them with wider loads or stores combined with rev
instructions. In some cases (i.e., with GCC version 5 and later)
this may result in unaligned accesses, which are not allowed before
we turn the MMU on.

So build any modules or static libraries that may execute with the MMU
off with -mstrict-align. Other modules don't need this switch, so we
can remove it from the CLANG35/AARCH64 common CC flags.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Liming Gao <liming.gao@intel.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@19638 6f19259b-4bc3-4df7-8a09-765794883524