Fix rewrite_nontemporals.c test to declare required alignment on variables
Fix rewrite_nontemporals.c test to declare required alignment on variables

The variables g_src and g_dest happened to be 16-byte aligned by luck
when we've run the test so far, but that wasn't guaranteed.  I noticed
that an unrelated change to libnacl happened to make them unaligned.

BUG= https://bugs.chromium.org/p/chromium/issues/detail?id=500026
TEST=run_rewrite_nontemporals_test (with other change applied)

Review URL: https://codereview.chromium.org/1835143002

sbc100/native_client,sbc100/native_client,sbc100/native_client,sbc100/native_client,sbc100/native_client,sbc100/native_client