Break bionic implementations into arch versions. DO NOT MERGE

Move arch specific code for arm, mips, x86 into separate
makefiles.
In addition, add different arm cpu versions of memcpy/memset.

Bug: 8005082

(cherry picked from commit acdde8c1cf8e8beed98c052757d96695b820b50c)

Change-Id: I0108d432af9f6283ae99adfc92a3399e5ab3e31d
16 files changed