[Indic] Allow halant group in Vowel and placeholder syllables

Fixes 2 out of 560 Devanagari failures.  AND:
Fixes 1 out of 2 Tamil failures.

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

@@ -67,11 +67,12 @@ matra_group = M.N?.H?;
 syllable_tail = SM? (Coeng (cn|V))? (VD VD?)?;
 place_holder = NBSP | DOTTEDCIRCLE;
 halant_group = (h.z?|z.h);
+halant_or_matra_group = (halant_group | matra_group*);
 
 
-consonant_syllable =	Repha? (cn.halant_group)* cn A? (halant_group | matra_group*)? syllable_tail;
-vowel_syllable =	reph? V.n? (halant_group.cn | ZWJ.cn)* matra_group* syllable_tail;
-standalone_cluster =	reph? place_holder.n? (halant_group.cn)* matra_group* syllable_tail;
+consonant_syllable =	Repha? (cn.halant_group)* cn A? halant_or_matra_group? syllable_tail;
+vowel_syllable =	reph? V.n? (halant_group.cn | ZWJ.cn)* halant_or_matra_group? syllable_tail;
+standalone_cluster =	reph? place_holder.n? (halant_group.cn)* halant_or_matra_group? syllable_tail;
 other =			any;
 
 main := |*

test/shaping/texts/in-tree/shaper-indic/indic/script-devanagari/misc/misc.txt

@@ -28,3 +28,4 @@
 र्अ्
 र्अ्‌
 र्अ्‍
+र्आ्र्