Swarming bots: add build products whitelist

Should reduce output isolate size (and therefore upload time) for
compile task by ~10x

NOTRY=true
BUG=skia:4763
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1768273002

Review URL: https://codereview.chromium.org/1768273002
1 file changed