[Indic] Position final subjoined consonants (and vowels) after matras

[Indic] Position final subjoined consonants (and vowels) after matras

In Khmer, a final subjoined consonant or independent vowel can occur
after matras.  This final subjoined thing should NOT be reordered to
before the matra even though it's subjoined.

Fixes another 1k of the Khmer failures.  Not much left really.