i915: Check return value of screen->image.loader->getBuffers

Ported from the i965 commit e7ab358e81.

Cc: 11.2 12.0 <mesa-stable@lists.freedesktop.org>
Cc: Tomasz Figa <tfiga@chromium.org>
Signed-off-by: Emil Velikov <emil.velikov@collabora.com>
Reviewed-by: Eric Engestrom <eric.engestrom@imgtec.com>

src/mesa/drivers/dri/i915/intel_context.c

@@ -858,6 +858,7 @@ intel_update_image_buffers(struct intel_context *intel, __DRIdrawable *drawable)
    struct __DRIimageList images;
    unsigned int format;
    uint32_t buffer_mask = 0;
+   int ret;
 
    front_rb = intel_get_renderbuffer(fb, BUFFER_FRONT_LEFT);
    back_rb = intel_get_renderbuffer(fb, BUFFER_BACK_LEFT);
@@ -877,12 +878,14 @@ intel_update_image_buffers(struct intel_context *intel, __DRIdrawable *drawable)
    if (back_rb)
       buffer_mask |= __DRI_IMAGE_BUFFER_BACK;
 
-   (*screen->image.loader->getBuffers) (drawable,
-                                        driGLFormatToImageFormat(format),
-                                        &drawable->dri2.stamp,
-                                        drawable->loaderPrivate,
-                                        buffer_mask,
-                                        &images);
+   ret = screen->image.loader->getBuffers(drawable,
+                                          driGLFormatToImageFormat(format),
+                                          &drawable->dri2.stamp,
+                                          drawable->loaderPrivate,
+                                          buffer_mask,
+                                          &images);
+   if (!ret)
+      return;
 
    if (images.image_mask & __DRI_IMAGE_BUFFER_FRONT) {
       drawable->w = images.front->width;