In GrConvertPixels, hoist pipeline creation out of the loop

This only impacts the case where we're doing a Y-flip, but there's no
reason to rebuild the pipeline for each row.

Change-Id: I64a231bbdb83819b1c22d2d3946035e832032bbd
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/572524
Commit-Queue: Brian Osman <brianosman@google.com>
Reviewed-by: Brian Salomon <bsalomon@google.com>
1 file changed