Bug swiftshader:15

Change-Id: Ia42d21b4f2c9e19a839ffb414661f2dffa350692
Reviewed-on: https://swiftshader-review.googlesource.com/7711Reviewed-by: Nicolas Capens <capn@google.com>
Tested-by: Nicolas Capens <capn@google.com>
Reviewed-on: https://swiftshader-review.googlesource.com/7630Reviewed-by: Alexis Hétu <sugoi@google.com>