Check for divide by zero in fill_in_2D_gaussian_kernel

Same change as the 1D one, but now with more dimensions!!

Bug: skia:7769
Change-Id: I152031780ab71ba106d4fa65d52960ec4358274e
Reviewed-on: https://skia-review.googlesource.com/118262
Commit-Queue: Greg Daniel <egdaniel@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
2 files changed