Remove legacy pixelref flag from bzl

NOTRY=true

Bug: skia:6535
Change-Id: I29d786cef240aaeaca829b4a9a25ff1a8f078588
Reviewed-on: https://skia-review.googlesource.com/15000
Reviewed-by: Matt Sarett <msarett@google.com>
Commit-Queue: Matt Sarett <msarett@google.com>
1 file changed