mmm_donut.py: Add options to stop munching based on MemFree or MemAvailable

BUG=b:336849237
TEST=mmm_donut.py on brya-banshee

Change-Id: Ia2f2ddc87f110dfbc4f888f65c538ea226527082
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/microbenchmarks/+/5593562
Tested-by: Renato Pereyra <renatopereyra@google.com>
Reviewed-by: Vovo Yang <vovoy@chromium.org>
Commit-Queue: Renato Pereyra <renatopereyra@google.com>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
1 file changed