Make fuzz autodetect file names

e.g.
out/ASAN/fuzz -b /path/to/file

Bug: skia:
Change-Id: I6df370a7f83e8ea8fc8c2dec20834620bc726911
Reviewed-on: https://skia-review.googlesource.com/122901
Reviewed-by: Mike Klein <mtklein@google.com>
Commit-Queue: Kevin Lubick <kjlubick@google.com>
1 file changed