Make fuzz output the words success for a 'clean exit'

The analysis looks for "Success" to determine if the fuzz should be considered
a clean exit or not.  It classifies clean exists as "grey" fuzzes, i.e. fixed.

TBR=mtklein@google.com
BUG=skia:4438
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1646603002

Review URL: https://codereview.chromium.org/1646603002
1 file changed