Add memcpy optimization pass for Skia samplers.

Adds an optimization to skia samplers that is using memcpy to copy the
pixels when the source and destination is the same size, unscaled, and
unfiltered.

Change-Id: I014db353e880cf09f3f0b17bbe7bcd2cc2d43d80
Signed-off-by: Henrik Smiding <henrik.smiding@stericsson.com>
Signed-off-by: Patrik Ryd <patrik.ryd@stericsson.com>