[myanmar] Allow punctuation clusters

The spec and Uniscribe don't allow these, but UTN#11
specifically says the sequence U+104B,U+1038 is valid.
As such, allow all "P V" sequences.  There's about
eight sequences that match that structure, but Roozbeh
thinks it's fine to allow all of them.

Test case: U+104B, U+1038

https://bugs.freedesktop.org/show_bug.cgi?id=71947

src/hb-ot-shape-complex-myanmar-machine.rl

@@ -61,6 +61,7 @@ VS   = 30;
 ZWJ  = 6;
 ZWNJ = 5;
 Ra   = 16;
+P    = 31;
 
 j = ZWJ|ZWNJ;			# Joiners
 k = (Ra As H);			# Kinzi
@@ -76,12 +77,14 @@ complex_syllable_tail = As* medial_group main_vowel_group post_vowel_group* pwo_
 syllable_tail = (H | complex_syllable_tail);
 
 consonant_syllable =	k? (c|IV|D|GB).VS? (H (c|IV).VS?)* syllable_tail;
+punctuation_cluster = 	P V;
 broken_cluster =	k? VS? syllable_tail;
 other =			any;
 
 main := |*
 	consonant_syllable	=> { found_syllable (consonant_syllable); };
 	j			=> { found_syllable (non_myanmar_cluster); };
+	punctuation_cluster	=> { found_syllable (punctuation_cluster); };
 	broken_cluster		=> { found_syllable (broken_cluster); };
 	other			=> { found_syllable (non_myanmar_cluster); };
 *|;

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

@@ -119,6 +119,7 @@ override_features_myanmar (hb_ot_shape_planner_t *plan)
 
 enum syllable_type_t {
   consonant_syllable,
+  punctuation_cluster,
   broken_cluster,
   non_myanmar_cluster,
 };
@@ -143,7 +144,8 @@ enum myanmar_category_t {
   OT_VBlw = 27,
   OT_VPre = 28,
   OT_VPst = 29,
-  OT_VS   = 30 /* Variation selectors */
+  OT_VS   = 30, /* Variation selectors */
+  OT_P    = 31  /* Punctuation */
 };
 
 
@@ -247,6 +249,10 @@ set_myanmar_properties (hb_glyph_info_t &info)
     case 0x108F: case 0x109A: case 0x109B: case 0x109C:
       cat = (indic_category_t) OT_SM;
       break;
+
+    case 0x104A: case 0x104B:
+      cat = (indic_category_t) OT_P;
+      break;
   }
 
   if (cat == OT_M)
@@ -409,6 +415,16 @@ initial_reordering_broken_cluster (const hb_ot_shape_plan_t *plan,
   initial_reordering_consonant_syllable (plan, face, buffer, start, end);
 }
 
+static void
+initial_reordering_punctuation_cluster (const hb_ot_shape_plan_t *plan HB_UNUSED,
+					hb_face_t *face HB_UNUSED,
+					hb_buffer_t *buffer HB_UNUSED,
+					unsigned int start HB_UNUSED, unsigned int end HB_UNUSED)
+{
+  /* Nothing to do right now.  If we ever switch to using the output
+   * buffer in the reordering process, we'd need to next_glyph() here. */
+}
+
 static void
 initial_reordering_non_myanmar_cluster (const hb_ot_shape_plan_t *plan HB_UNUSED,
 					hb_face_t *face HB_UNUSED,
@@ -429,6 +445,7 @@ initial_reordering_syllable (const hb_ot_shape_plan_t *plan,
   syllable_type_t syllable_type = (syllable_type_t) (buffer->info[start].syllable() & 0x0F);
   switch (syllable_type) {
   case consonant_syllable:	initial_reordering_consonant_syllable  (plan, face, buffer, start, end); return;
+  case punctuation_cluster:	initial_reordering_punctuation_cluster (plan, face, buffer, start, end); return;
   case broken_cluster:		initial_reordering_broken_cluster      (plan, face, buffer, start, end); return;
   case non_myanmar_cluster:	initial_reordering_non_myanmar_cluster (plan, face, buffer, start, end); return;
   }