dwrite: Mark features that were not found.

dlls/dwrite/dwrite_private.h

@@ -544,6 +544,7 @@ enum shaping_feature_flags
     FEATURE_MANUAL_ZWJ = 0x8,
     FEATURE_MANUAL_JOINERS = FEATURE_MANUAL_ZWNJ | FEATURE_MANUAL_ZWJ,
     FEATURE_HAS_FALLBACK = 0x10,
+    FEATURE_NEEDS_FALLBACK = 0x20,
 };
 
 struct shaping_feature

dlls/dwrite/opentype.c

@@ -4568,6 +4568,8 @@ static void opentype_layout_collect_lookups(struct scriptshaping_context *contex
             next_bit += bits_needed;
             context->global_mask |= (feature->default_value << feature->shift) & feature->mask;
         }
+        if (!found)
+            feature->flags |= FEATURE_NEEDS_FALLBACK;
     }
 
     for (stage = 0; stage <= features->stage; ++stage)