Fix glReadPixels and glClear memory leaks. Bug 26486408 Change-Id: Iec34ee0034695950163e8e40082d1ad7128490f8 Reviewed-on: https://swiftshader-review.googlesource.com/4533 Reviewed-by: Alexis Hétu <sugoi@google.com> Tested-by: Nicolas Capens <capn@google.com> Reviewed-by: Nicolas Capens <capn@google.com>