[arabic-fallback] Add the component loop

Should be able to support 3-letter ligatures now.  Hooking up next.

src/hb-ot-shaper-arabic-fallback.hh

@@ -153,13 +153,16 @@ arabic_fallback_synthesize_lookup_ligature (const hb_ot_shape_plan_t *plan HB_UN
       const auto &components = ligature_table[first_glyph_idx].ligatures[ligature_idx].components;
       unsigned component_count = ARRAY_LENGTH_CONST (components);
 
-      hb_codepoint_t component_u   = ligature_table[first_glyph_idx].ligatures[ligature_idx].components[0];
-      hb_codepoint_t component_glyph;
-      if (!component_u ||
-	  !hb_font_get_glyph (font, component_u,   0, &component_glyph))
-	continue;
+      for (unsigned i = 0; i < component_count; i++)
+      {
+	hb_codepoint_t component_u   = ligature_table[first_glyph_idx].ligatures[ligature_idx].components[i];
+	hb_codepoint_t component_glyph;
+	if (!component_u ||
+	    !hb_font_get_glyph (font, component_u,   0, &component_glyph))
+	  continue;
 
-      component_list[num_components++] = component_glyph;
+	component_list[num_components++] = component_glyph;
+      }
 
       component_count_list[num_ligatures] = 1 + component_count;
       ligature_list[num_ligatures] = ligature_glyph;