Slightly faster.  In prep for more changes.

Saves some time.  Also preparing for reusing the ccc byte for other stuff.

...at compile time.

Also route fuzzing-related tests through hb-ot-font, to reduce dependency
on FreeType behavior for badly-broken fonts.  Fixes failing test with
FreeType master.

Fixes https://github.com/behdad/harfbuzz/issues/152

https://bugzilla.mozilla.org/show_bug.cgi?id=1215894

https://bugzilla.mozilla.org/show_bug.cgi?id=1215894

https://bugzilla.mozilla.org/show_bug.cgi?id=1215894

From https://bugzilla.mozilla.org/show_bug.cgi?id=1215894

Fixes https://github.com/behdad/harfbuzz/issues/146

Or I think it should.

Borrowed from https://bugzilla.mozilla.org/show_bug.cgi?id=1215411

Add BUILD.md based on harfbuzz.org docs

[ci] change to docker infrastructure

The default FreeType load flags where changed from FT_LOAD_NO_HINTING
to FT_LOAD_DEFAULT in 2a9627c5.
This is crashing HarfBuzz-enabled FreeType as I suppose it causes
infinite recursion between HB and FT autohinter...

Revert the behavior change.

Fixes https://github.com/behdad/harfbuzz/issues/143

From:
https://github.com/behdad/harfbuzz/issues/139#issuecomment-147616887
https://github.com/behdad/harfbuzz/issues/139#issuecomment-148289957

Discovered by libFuzzer.  Ouch!

https://github.com/behdad/harfbuzz/issues/139#issuecomment-148289957

We probably should implement better system to catch cyclic lookups.
But for now, this speeds up worst case behavior with broken fonts
considerably without compromising legitimate usecases.

https://github.com/behdad/harfbuzz/issues/139#issuecomment-147788447

https://github.com/behdad/harfbuzz/issues/139#issuecomment-147616887

Fixes https://github.com/behdad/harfbuzz/issues/139#issuecomment-146984679

https://github.com/behdad/harfbuzz/issues/139

Also discovered by "libFuzzer".

This is a fix on top of the previous issue fixed in
c917965b.

This was caught by "libFuzzer" testing.

No reason to not have it.  Makes life easier later.
We (hb-ft, hb-ot-font, etc) can use this API to inject new
parent into a font...

This changes the default load_flags of fonts created using
hb_ft_font_create() from NO_HINTING to DEFAULT.  Hope that doesn't
break too much client code.

Code calling hb_ft_font_set_funcs() is unaffected.