Ensure that all driver functions use the signature of the service or driver.
This avoids pointer mismatches, which are technically undefined behaviour.
Recent compilers are more picky in catching them as part of Control Flow
Integrity tests.
This is mandated by the C99 standard, and clang 15 produces zillions of
warnings otherwise.
* devel/ftoption.h, include/freetype/config/ftoption.h,
include/freetype/internal/ftmemory.h, src/autofit/afhints.h,
src/autofit/afmodule.c, src/autofit/aftypes.h, src/base/ftadvanc.c,
src/base/ftdbgmem.c, src/base/ftstream.c, src/bdf/bdflib.c,
src/truetype/ttinterp.c: Replace identifiers of the form `_foo` with `foo_`.
The binary searches within charmaps can be accelerated because they
often contain dense continuous blocks of character codes. Within such
blocks, you can predict matches based on misses. This method has been
deployed in `bdf` since 0f122fef34; we only refactor it there. We now
use it in `pfr` and `psnames`, which speeds up the unicode charmap
access by about 50% in PFR and Type 1 fonts.
* src/bdf/bdfdrivr.c (bdf_cmap_char_{index,next}): Refactor.
* src/pfr/pfrcmap.c (pfr_cmap_char_{index,next}): Predict `mid` based
on the mismatch distance.
* src/psnames/psmodule.c (ps_unicodes_char_{index,next}): Ditto.
* src/sfnt/ttcolr.c (FT_PaintFormat_Internal): New enumeration values
`FT_COLR_PAINTFORMAT_INTERNAL_VAR_SKEW`,
`FT_COLR_PAINTFORMAT_INTERNAL_SKEW_CENTER`, and
`FT_COLR_PAINTFORMAT_INTERNAL_VAR_SKEW_CENTER`.
(read_paint): Handle new enumeration values.