[build] Fix multi and C++ builds.
The following builds were failing due to previous changes:
make multi
make multi CC="c++"
* include/freetype/config/ftconfig.h: Remove `FT_END_HEADER'.
* include/freetype/config/ftheader.h (FT_BEGIN_HEADER,
FT_END_HEADER): Protect against redefinition.
* src/cache/ftccache.h, src/cache/ftcmru.h, src/pcf/pcfutil.h,
src/psaux/pserror.h, src/psaux/psft.h, src/psaux/psstack.h,
src/sfnt/woff2tags.h: Include `compiler-macros.h'.
* src/sfnt/woff2tags.c: Include `woff2tags.h'.
11 files changed
