Row major matrix packing wasn't properly detected when the layout
qualifier was on the block member rather than on the block itself
or when a nested structure had a matrix packing qualifier.

Fixes all failing tests in:
deqp/functional/gles3/uniformbuffers*

No regressions in:
dEQP-GLES3.functional.ubo*

Change-Id: I1549a70c4286a8a84b695bc876d71d9cf636b306
Reviewed-on: https://swiftshader-review.googlesource.com/16588Tested-by: Alexis Hétu <sugoi@google.com>
Reviewed-by: Nicolas Capens <nicolascapens@google.com>