[Thai] Reorder U+0E3A THAI VOWEL SIGN PHINTHU

Uniscribe reorders U+0E3A to be after U+0E38 and U+0E39.  We do that by
modifying the ccc for U+0E3A.

Fixes the two remaining Thai failures (see previous commit).

src/hb-ot-shape-complex-misc.cc

@@ -132,6 +132,13 @@ _hb_ot_shape_complex_setup_masks_thai (hb_ot_map_t *map HB_UNUSED,
    * chattawa.
    *
    * Same for Lao.
+   *
+   * Note:
+   *
+   * Uniscribe also does so below-marks reordering.  Namely, it positions U+0E3A
+   * after U+0E38 and U+0E39.  We do that by modifying the ccc for U+0E3A.
+   * See _hb_unicode_modified_combining_class ().  Lao does NOT have a U+0E3A
+   * equivalent.
    */
 
 

src/hb-unicode.cc

@@ -363,6 +363,12 @@ _hb_unicode_modified_combining_class (hb_unicode_funcs_t *ufuncs,
     };
     c = permuted_hebrew_classes[c - 10];
   }
+  else if (unlikely (unicode == 0x0E3A)) /* THAI VOWEL SIGN PHINTHU */
+  {
+    /* Assign 104, so it reorders after the THAI ccc=103 marks.
+     * Uniscribe does this. */
+    c = 104;
+  }
 
   return c;
 }

test/shaping/texts/in-tree/shaper-thai/script-thai/misc/MANIFEST

@@ -1 +1,2 @@
+phinthu.txt
 sara-am.txt

test/shaping/texts/in-tree/shaper-thai/script-thai/misc/phinthu.txt

@@ -0,0 +1,16 @@
+ป
+ปฺ
+ปุ
+ปู
+ปุู
+ปูุ
+ปฺุ
+ปฺุ
+ปฺู
+ปฺู
+ปฺุู
+ปฺุู
+ปฺุู
+ปฺูุ
+ปฺูุ
+ปฺูุ