Implement clone() for 4 additional GrFragmentProcessor subclasses

HighContrastFilterEffect
LumaColorFilterEffect
OverdrawFragmentProcessor
RRectsGaussianEdgeFP

Change-Id: Ie843e025e49dd46e3f75a5f79d399ddd3ceba5cd
Reviewed-on: https://skia-review.googlesource.com/26660
Commit-Queue: Brian Salomon <bsalomon@google.com>
Reviewed-by: Greg Daniel <egdaniel@google.com>
4 files changed