Fuzz: use SkNullWStream

Change-Id: I2ed989b10671f4acf9aa3e25c5bcb709630cb9e9
Reviewed-on: https://skia-review.googlesource.com/38961
Commit-Queue: Ben Wagner <bungeman@google.com>
Reviewed-by: Ben Wagner <bungeman@google.com>
1 file changed