link gdbserver against libiberty

This builds a libiberty just for gdbserver and arranges for gdbserver
to use it.  I've tripped across the lack of libiberty in gdbserver at
least once, and I have seen other threads where it would have been
useful.

2014-06-12  Tom Tromey  <tromey@redhat.com>

	* debug.c (debug_printf): Remove HAVE_GETTIMEOFDAY checks.
	* server.c (monitor_show_help): Remove HAVE_GETTIMEOFDAY check.
	(parse_debug_format_options): Likewise.
	(gdbserver_usage): Likewise.
	* Makefile.in (LIBIBERTY_BUILDDIR, LIBIBERTY): New variables.
	(SUBDIRS, REQUIRED_SUBDIRS): Add libiberty.
	(gdbserver$(EXEEXT), gdbreplay$(EXEEXT)): Depend on and link
	against libiberty.
	($(LIBGNU)): Depend on libiberty.
	(all-lib): Recurse into all subdirs.
	(install-only): Invoke "install" target in subdirs.
	(vasprintf.o, vsnprintf.o, safe-ctype.o, lbasename.o): Remove
	targets.
	* configure: Rebuild.
	* configure.ac: Add ACX_CONFIGURE_DIR for libiberty.  Don't check
	for vasprintf, vsnprintf, or gettimeofday.
	* configure.srv: Don't add safe-ctype.o or lbasename.o to
	srv_tgtobj.