Positional sub-categories not applied yet.

Though, looks like gcc was smart enough to produce the same code
before...

Touch code just enough to preserve previous syllable structure
and functionality as closely as possible.  Many further cleanups
coming later.

No output change.

We don't need Indic table for those.

-#define indic_offset_total 4416
+#define indic_offset_total 3816

-}; /* Table occupancy: 60% */
+}; /* Table occupancy: 69% */

No functional change.

Handles Tai Tham, Cham, and New Tai Lue for now.

Not hooked up yet.

Nothing functional in there yet.

So far, we're parsing IndicSyllabicCategory.txt and IndicMatraCategory.txt
fils from Unicode Character Database and store them in an array to be used
by the shaper.  Also hooked up the shaper, but it does not do anything
right now.