build: Remove WindowsCE support from mkheader.
* src/assuan.h.in (@include:sys/types.h@, @include:unistd.h@): Simply include <sys/types.h> and <unistd.h>. (@include:w32ce-add@): Remove. * src/mkheader.c (write_special): Remove mingw32ce support.
- GnuPG-bug-id: T6170
- Signed-off-by: NIIBE Yutaka <gniibe@fsij.org>