ozone: Use a non-empty usage flag when checking formats with minigbm

minigbm doesn't support passing an empty usage flag to
gbm_device_is_format_supported(), which could happen with the
previous code if the format isn't scanout-able.

GBM_BO_USE_TEXTURING is an enum value and thus its existence
cannot be checked with the preprocessor.

Bug: 882429
Change-Id: I824dca82be65fdb6ffb8ab1e729af424e8969200
Reviewed-on: https://chromium-review.googlesource.com/1215947Reviewed-by: Maksim Sisov <msisov@igalia.com>
Reviewed-by: Michael Spang <spang@chromium.org>
Commit-Queue: Michael Spang <spang@chromium.org>
Cr-Commit-Position: refs/heads/master@{#589957}

ui/ozone/common/linux/gbm_wrapper.cc

@@ -308,7 +308,7 @@ class Device final : public ui::GbmDevice {
 
     // Try to use scanout if supported.
     int gbm_flags = GBM_BO_USE_SCANOUT;
-#if defined(GBM_BO_USE_TEXTURING)
+#if defined(USING_MINIGBM)
     gbm_flags |= GBM_BO_USE_TEXTURING;
 #endif
     if (!gbm_device_is_format_supported(device_, format, gbm_flags))