* configure.in: Add calls to AC_CONFIG_HEADER, AC_CHECK_HEADERS,

	* configure.in: Add calls to AC_CONFIG_HEADER, AC_CHECK_HEADERS,
	AC_CHECK_LIB, and AC_CHECK_FUNCS.  Change AC_OUTPUT to set
	stamp-h.
	* configure: Rebuild.
	* config.in: New file, generated by autoheader.
	* interp.c: Include "config.h".  Include <stdlib.h>, <string.h>,
	and <strings.h> if they exist.  Replace #ifdef sun with #ifdef
	HAVE_ANINT and HAVE_AINT, as appropriate.
	* Makefile.in (run): Use @LIBS@ rather than -lm.
	(interp.o): Depend upon config.h.
	(Makefile): Just rebuild Makefile.
	(clean): Remove stamp-h.
	(mostlyclean): Make the same as clean, not as distclean.
	(config.h, stamp-h): New targets.