mesa/st: Abort the linking on driver link failure.

If the driver said it can't do the shader, then listen to it and don't ask
it to create the shaders anyway.  Fixes a bunch of spam on i915/r300 (with
!16878) about unsupported opcodes during dEQP runs.

Reviewed-by: Timothy Arceri <tarceri@itsqueeze.com>
Reviewed-by: Adam Jackson <ajax@redhat.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/16895>

src/mesa/state_tracker/st_glsl_to_nir.cpp

@@ -851,7 +851,7 @@ st_link_nir(struct gl_context *ctx,
       char *msg = st_glsl_to_nir_post_opts(st, shader->Program, shader_program);
       if (msg) {
          linker_error(shader_program, msg);
-         break;
+         return false;
       }
 
       if (prev_info &&