Change vendor features from Harf/Buzz to HARF/BUZZ

https://github.com/harfbuzz/harfbuzz/commit/a01194aaf4c15160330b4042066263b2c963b658#commitcomment-30772041

"The tag space of tags consisting of four uppercase letters (A-Z) with no punctuation,
spaces, or numbers, is reserved as a vendor space. Font vendors may use such tags to
identify private features."

src/hb-ot-shape.cc

@@ -132,12 +132,12 @@ hb_ot_shape_collect_features (hb_ot_shape_planner_t          *planner,
   /* Random! */
   map->enable_feature (HB_TAG ('r','a','n','d'), F_RANDOM, HB_OT_MAP_MAX_VALUE);
 
-  map->enable_feature (HB_TAG('H','a','r','f'));
+  map->enable_feature (HB_TAG('H','A','R','F'));
 
   if (planner->shaper->collect_features)
     planner->shaper->collect_features (planner);
 
-  map->enable_feature (HB_TAG('B','u','z','z'));
+  map->enable_feature (HB_TAG('B','U','Z','Z'));
 
   for (unsigned int i = 0; i < ARRAY_LENGTH (common_features); i++)
     map->add_feature (common_features[i]);