Align `char_next` return types.

This is mostly cosmetic because FT_UInt and FT_UInt32 are likely identical.

* src/sfnt/ttcmap.c, src/cff/cffcmap.c, src/psaux/t1cmap.c,
src/psnames/psmodule.c, include/freetype/internal/service/svpcsmap.h,
src/pfr/pfrcmap.c, src/winfonts/winfnt.c (*_char_next): return FT_UInt.
7 files changed