Implement support for RGBA blitting.
Implement support for RGBA blitting.

Change-Id: I1ad9fed9aea34cd20f8d78f4d4469c61aeb00ea6
Reviewed-on: https://swiftshader-review.googlesource.com/2753
Reviewed-by: Nicolas Capens <0612353e1fcebbfd4b302d9337447ca0cdfa9122@google.com>
Tested-by: Nicolas Capens <0612353e1fcebbfd4b302d9337447ca0cdfa9122@google.com>

bkaradzic/SwiftShader,google/swiftshader,bkaradzic/SwiftShader,bkaradzic/SwiftShader,google/swiftshader,google/swiftshader,bkaradzic/SwiftShader,bkaradzic/SwiftShader