Bug swiftshader:15

Change-Id: I0d9cb2daeea931994abeb63f0939879875d4e81f
Reviewed-on: https://swiftshader-review.googlesource.com/7791Reviewed-by: Nicolas Capens <capn@google.com>
Tested-by: Nicolas Capens <capn@google.com>
Reviewed-on: https://swiftshader-review.googlesource.com/8148Reviewed-by: Alexis Hétu <sugoi@google.com>