Fixes a double free.

Change-Id: Ieb71dff4476132b9b2fb624223e26af49a4131ee
Reviewed-on: https://swiftshader-review.googlesource.com/9728Reviewed-by: Alexis Hétu <sugoi@google.com>
Reviewed-by: Nicolas Capens <capn@google.com>
Tested-by: Nicolas Capens <capn@google.com>