In a lot of cases, int was being used instead of size_to represent
sizes. That led to some warnings about inconsistencies between int
and size_t usage. While this cl doesn't solve all warnings, it tries
to use size_t and int where it should be appropriate to use them.

Change-Id: Id760df1360f65b2bba60f4075cdf4954fc6bbaf3
Reviewed-on: https://swiftshader-review.googlesource.com/5177Reviewed-by: Alexis Hétu <sugoi@google.com>
Reviewed-by: Nicolas Capens <capn@google.com>
Tested-by: Alexis Hétu <sugoi@google.com>