Move declaration of is_fuzzer to where it is used

BUG=skia:6260

Change-Id: Iaca4fb1afb4d182f4d2ae64d939729363a226ce6
Reviewed-on: https://skia-review.googlesource.com/8772
Reviewed-by: Kevin Lubick <kjlubick@google.com>
Commit-Queue: Ravi Mistry <rmistry@google.com>
2 files changed