See comments.

We should add a bot for it
Part of #1652

Fixes an unused function warning when building with HB_NO_SUBSET_LAYOUT
as part of the Chrome build.

https://github.com/grigorig/ucdn/issues/23

Part of https://github.com/harfbuzz/harfbuzz/issues/1652

No idea where these appear from...

This make output of hb_enumerate() sorted regardless of input iterator.

More correct behavior.  We were commenting out some legit conditions
before.

Part of https://github.com/harfbuzz/harfbuzz/issues/1652

Part of https://github.com/harfbuzz/harfbuzz/issues/1652

Fixes https://github.com/harfbuzz/harfbuzz/issues/1709

Part of https://github.com/harfbuzz/harfbuzz/issues/1652

This reverts commit 9b05db33.

Fixes https://github.com/harfbuzz/harfbuzz/issues/1708

This reverts commit ae8719eb.

Part of https://github.com/harfbuzz/harfbuzz/issues/1708

Fedora upgraded to ragel 7, which is buggy if char is signed.
Switching to -G2 output fails with sign-compare error:

../../src/hb-buffer-deserialize-json.hh:107:12: error: comparison of integer expressions of different signedness: ‘unsigned int’ and ‘const char’ [-Werror=sign-compare]
    if ( 9u <= ( (*( p))) && ( (*( p))) <= 13u ) {
         ~~~^~~~~~~~~~~~~

Switching to -T1 for now.  It actually results in smaller code,
at the expense of some binary searching instead of flat tables.
In the not distant future, we might actually generate two different
outputs and choose between depending on size-optimize options.

Fixes https://github.com/harfbuzz/harfbuzz/issues/1708

Assumning subsetter would be used for printing-like uses in that case,
which don't need GSUB/GPOS.

Part of https://github.com/harfbuzz/harfbuzz/issues/1652

Part of https://github.com/harfbuzz/harfbuzz/issues/1652

[Docs] Add gtk-doc comments for OT color and OT math

Now that user can override it if needed...

Part of https://github.com/harfbuzz/harfbuzz/issues/1652

Subsetter size goes down from 190kb to 119kb.  Main library about 7kb.

Part of https://github.com/harfbuzz/harfbuzz/issues/1652

style fix and add return statement