NaCL has been disabled for awhile, so the code
will still build, but only with C versions.
This change removes the MEMACCESS() macros from
Neon and Neon64 source.

BUG=libyuv:702
TEST=try bots build for arm.
R=kjellander@chromium.org

Change-Id: Id581a5c8ff71e18cc69595e7fee9337f97c44a19
Reviewed-on: https://chromium-review.googlesource.com/528332Reviewed-by: Cheng Wang <wangcheng@google.com>
Commit-Queue: Frank Barchard <fbarchard@google.com>