Fix toplevel config.status for HP-UX sed.

Fix toplevel config.status for HP-UX sed.

/:
	* configure.ac: Do not use $extrasub for replacing @if/@endif
	parts in Makefile; instead, use additional arguments to
	AC_CONFIG_COMMANDS to do the replacement manually, with several
	sed invocations, to avoid HP-UX sed command limits.
	* configure: Regenerate.