* configure.in: Convert to use autoconf.

	* configure.in: Convert to use autoconf.
	* configure: New file, built by autoconf.
	* acconfig.h: New file.
	* config.in: New file, built by autoheader.
	* Makefile.in: Various changes for new configure script.  Also:
	(INSTALL): Go up two levels, not one.
	(ALLOCA, MALLOC, OPCODES): Remove.
	(gencode): Use $(CC_FOR_BUILD).
	(case.o): Remove.
	(run.o, interp.o): Depend upon config.h.
	* interp.c: Include "config.h".  Don't include "sysdep.h".
	Include <stdlib.h>, <time.h>, and <unistd.h> if they exist.
	* run.c: Include "config.h".  Don't include "sysdep.h".  Include
	<stdlib.h> if it exists.  Include "getopt.h".  Declare printf if
	necessary.