glamor: Fix possible double-free

If glamor_link_glsl_prog() fails, we may jump to the failed code path which frees the variable vs_prog_string and fs_prog_string.

But those variables were already freed just before, so in that case we end up freeing the memory twice.

Simply move the free at the end of the success code path so we are sure to free the values only once, either in the successful of failed code paths.

Fixes: 2906ee5e - glamor: Fix leak in glamor_build_program()
Signed-off-by: Olivier Fourdan ofourdan@redhat.com

Note: Found by a static analysis tool