* configure.in: Rename libFOO to target-libFOO, and xiberty

	* configure.in:  Rename libFOO to target-libFOO, and xiberty
	to target-xiberty, to provide more flexibility.
	(target_subdir):  Define.  Create if cross.
	Set TARGET_SUBDIR in Makefile to ${target_subdir}.
	* Makefile.in:  Rename all-libFOO -> all-target-libFOO, all-xiberty
	-> all-target-libiberty, configure-libFOO -> configure-target-libFOO,
	check-libFOO -> check-target-libFOO, etc.
	($(DO_X)):  Iterate over TARGET_CONFIGDIRS after SUBDIRS.
	($(CONFIGURE_TARGET_MODULES), $(CHECK_TARGET_MODULES),
	$(ALL_TARGET_MODULES), $(INSTALL_TARGET_MODULES)): Update accordingly.
	(configure-target-XXX):  Depend on $(ALL_GCC), not all-gcc, to
	allow ALL_GCC="" to only configure.
	(DEVO_SUPPORT):  Add cfg-ml-com.in and cfg-ml-pos.in.
	(ETC_SUPPORT, ETC_SUPPORT_PFX):  Merge;  update 'taz' accordingly.
	(LIBGXX_SUPPORT_DIRS):  Remove xiberty.