Fix errors on tree.

The test didn't account for platforms where SK_HAS_MUSTTAIL is
false (non-Clang compilers, Clang + ARM).

Change-Id: Ie6a05da6c50773cbed15f9a2d9193c47098030ce
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/633176
Reviewed-by: Arman Uguray <armansito@google.com>
Commit-Queue: Arman Uguray <armansito@google.com>
Commit-Queue: John Stiles <johnstiles@google.com>
Auto-Submit: John Stiles <johnstiles@google.com>
1 file changed