zink: do not ask glsl-compiler to unroll

We don't really need loops unrolled, so let's just disable this. This is
generally recommended for NIR drivers, but we can do even better; not
even unroll in NIR. And since we don't set
nir_shader_compiler_options::max_unroll_iterations, we're already there.

Reviewed-By: Mike Blumenkrantz <michael.blumenkrantz@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/10487>

src/gallium/drivers/zink/zink_screen.c

@@ -740,7 +740,7 @@ zink_get_shader_param(struct pipe_screen *pscreen,
       return 0; /* no idea */
 
    case PIPE_SHADER_CAP_MAX_UNROLL_ITERATIONS_HINT:
-      return 32; /* arbitrary */
+      return 0;
 
    case PIPE_SHADER_CAP_MAX_SHADER_BUFFERS:
       switch (shader) {