Support for building as a shared library, based on patches from

	Support for building as a shared library, based on patches from
	Alan Modra <alan@spri.levels.unisa.edu.au>:
	* configure.in: Add AC_ARG_ENABLE for shared and commonbfdlib.
	New substitutions: ALLLIBS, PICFLAG, SHLIB, SHLIB_CC,
	SHLIB_CFLAGS, COMMON_SHLIB, SHLINK.
	* configure: Rebuild.
	* Makefile.in (ALLLIBS): New variable.
	(PICFLAG, SHLIB, SHLIB_CC, SHLIB_CFLAGS): New variables.
	(COMMON_SHLIB, SHLINK): New variables.
	(.c.o): If PICFLAG is set, compile twice, once PIC, once normal.
	(STAGESTUFF): Remove variable.
	(all): Depend upon $(ALLLIBS) rather than $(TARGETLIB).
	(stamp-piclist, piclist): New targets.
	($(SHLIB), $(SHLINK)): New targets.
	($(OFILES)): Depend upon stamp-picdir.
	(disassemble.o): Build twice if PICFLAG is set.
	(MOSTLYCLEAN): Add pic/*.o.
	(clean): Remove $(SHLIB), $(SHLINK), piclist, and stamp-piclist.
	(distclean): Remove pic and stamp-picdir.
	(install): Install shared libraries.
	(stamp-picdir): New target.