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

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

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

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

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

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

It was cumbersome to get it to work reliably, for dubious performance
gain, mostly in the subsetter maybe...

Life is easier without.  It was disabled forever anyway.

Was wrong.  The returned pointer couldn't be passed to free().  Ouch!

Introduced in aa3450ca, let's preserve it

Hopefullly.

This makes it possible to include all .cc files into build, even if not
building CoreText, Uniscribe, etc.

This was mostly to help custom builders.  But also means that we can
include all files in our own build system.  Not sure if we should.
Definitely simplifies things, but slightly only.

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

This disables fallback shaper in tiny builds.  Projects that don't
use our build system and want to disable fallback shaper (eg. Firefox)
should define HB_NO_FALLBACK_SHAPE now.

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

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

https://github.com/googlefonts/harfbuzz/commit/9f610ae239a11e86f94621e26bc15849b65ce41b#commitcomment-33944686

Part of https://github.com/harfbuzz/harfbuzz/issues/1682

This reverts commit 47030b18.

Reverts only the hb-ft part, to reinstate non-OpenType kerning with
FreeType.

Fixes https://github.com/harfbuzz/harfbuzz/issues/1682

This reverts commit d219f899.

API change: Un-deprecate font kern API.

Part of https://github.com/harfbuzz/harfbuzz/issues/1682

We should document that this API is only necessary to hook up
non-OpenType kerning.  hb-ot-font will continue to NOT implement them.

add Unicode UCS-4 cmap
fix Unicode bits in OS/2
add Unicode cmap sub-table in SourceHanSans-Regular_subset.otf
regenerate cff subset test expected results

Added in 01dff1ea and 19256bef, this was targeted at older
msvc versions that don't support C99 but now as we require
C++11 we don't target places those envs thus removing this.

+this works on gcc 4.8 as well as default code path.

This reverts commit a0c49007.

Just testing bots.  Will finish based on results.