renderer: if the srgb state changes dirty samplers

srgb decode is part of sampler state, so if we are using
samplers just dirty the sampler state.

fixes: tex-srgb

src/vrend_renderer.c

@@ -1668,10 +1668,14 @@ void vrend_set_single_sampler_view(struct vrend_context *ctx,
             tex->cur_swizzle_a = view->gl_swizzle_a;
          }
          if (tex->srgb_decode != view->srgb_decode && util_format_is_srgb(tex->base.base.format)) {
+	    if (vrend_state.have_samplers)
+	       ctx->sub->sampler_state_dirty = TRUE;
+	    else {
 	       glTexParameteri(view->texture->target, GL_TEXTURE_SRGB_DECODE_EXT,
 			       view->srgb_decode);
 	       tex->srgb_decode = view->srgb_decode;
 	    }
+         }
       } else {
 	GLenum internalformat;
          tex = (struct vrend_texture *)view->texture;