Fixes https://github.com/harfbuzz/harfbuzz/issues/1300

Not sure I've marked all such structs.  To be done as we discover.

Fixes https://github.com/harfbuzz/harfbuzz/issues/1300

So, our fallback static_assert cannot be had more than once per line
of source.

Bots not happy with using "this" inside assertion...

This reverts 26566448

Test U+111C9 SHARADA SANDHI MARK

Fix USE categories for U+111C9 SHARADA SANDHI MARK

That's better use of that value than requiring extra macro HB_NO_ATEXIT

New version has axis flags.

New API:
+hb_ot_var_axis_info_t
+hb_ot_var_find_axis_info()
+hb_ot_var_get_axis_infos()

Deprecated API:
-HB_OT_VAR_NO_AXIS_INDEX
-hb_ot_var_axis_t
-hb_ot_var_find_axis()
-hb_ot_var_get_axes()

Shrink the emoji table by merging adjacent ranges

Ouch.  Wonder how none of the bots caught the float->int truncation.

Fixes https://github.com/harfbuzz/harfbuzz/issues/1241

Part of https://github.com/harfbuzz/harfbuzz/issues/1241

New API:
+hb_ot_var_axis_flags_t
+hb_ot_var_axis_get_flags

Unfortunate that we don't have room in hb_ot_var_axis_t to expose flags :(.