microbenchmarks: update to _FORTIFY_SOURCE=3

Since this project explicitly specifies its FORTIFY level, update it to
the level CrOS wants to move to. This isn't _removed_, since it's copied
from a template file, and consistency with that seems useful.

BUG=b:288411201
TEST=CQ+1

Change-Id: I38321ba9cc61f756907b62b519542f5f070791ae
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/microbenchmarks/+/4707192
Reviewed-by: Vovo Yang <vovoy@chromium.org>
Tested-by: George Burgess <gbiv@chromium.org>
Commit-Queue: George Burgess <gbiv@chromium.org>
1 file changed