[indic] Always start new syllable for Avagraha

In fact, the previous grammar was ambigious.  No functional
change.

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

@@ -70,7 +70,7 @@ forced_rakar = ZWJ H ZWJ Ra;
 symbol = Symbol.N?;
 matra_group = z{0,3}.M.N?.(H | forced_rakar)?;
 syllable_tail2 = (SM.SM?.ZWNJ?)? A{0,3}? VD{0,2};
-syllable_tail =  (Coeng (cn|V))? symbol? syllable_tail2;
+syllable_tail =  (Coeng (cn|V))? syllable_tail2;
 place_holder = NBSP | DOTTEDCIRCLE;
 halant_group = (z?.h.(ZWJ.N?)?);
 final_halant_group = halant_group | h.ZWNJ;