Pixel store parameters

Adding the missing pixel store
parameters needed to use some
tests. Added the UnpackInfo
structure to minimize function
signature changes while sending
all unpack parameters to
loadImageData().

Change-Id: I86b660697ae726f902923066a9defe6d3a88860f
Reviewed-on: https://swiftshader-review.googlesource.com/2943
Tested-by: Alexis Hétu <sugoi@google.com>
Reviewed-by: Nicolas Capens <capn@google.com>
9 files changed