Fix handing of `FT_Bool'.

Before this commit we had code like

  (FT_Bool)( globals->glyph_styles[gindex] & 0x8000)

Since `FT_Bool' is defined to be an `unsigned char', the code
evaluated to something like

  (unsigned char)( 0x8532 & 0x8000)

which in turn expanded to

  (unsigned char)( 0x8000)

and finally yielded 0x00 – i.e., false – not as expected.

Problem reported and analyzed by Tony Smith <tony.smith@macro4.com>.

* include/freetype/fttypes.h (FT_BOOL): Add a comparison against
zero so that we always have a Boolean expression.

*/*: Replace castings to `FT_Bool' with calls to `FT_BOOL' where
possible.
19 files changed