Check for <unistd.h>.

Check for <unistd.h>.

2000-08-02  Tor Lillqvist  <tml@iki.fi>

	* configure.in: Check for <unistd.h>.

2000-08-02  Tor Lillqvist  <tml@iki.fi>

	* io-bmp.c
	* io-ico.c
	* io-ras.c
	* io-tiff.c
	* io-wbmp.c: Conditionalise inclusion of <unistd.h>.

	* makefile.mingw.in: List loaders alphabetically. Add the wbmp
	one. Fix names of DLLs to have '-' instead of '_'.