archives and plugin target

archives and plugin target

Automatically choosing "plugin" for the archive target when plugins
are enabled can result in making archives as specified by the plugin
target vec, ie. COFF style archives (also used by most ELF
binutils targets).  This is wrong for aix, hpux, vms, aout, macho
and possibly other targets, if compatibility with target system
archives matters.

This patch removes archive support entirely from the plugin target.
That means an archive will never get past bfd_check_format with a
target of plugin_vec, even if it is opened using "plugin".  Instead,
archives will have their elements opened using the plugin target
selected is such a way that the plugin target will be tried first in
bfd_check_format and then continue to try other targets if that fails.

The patch tries to avoid opening archives using "plugin" because that
is guaranteed to fail the first target check in bfd_check_format, but
mm.c still does so, and nested archives will also be opened using
"plugin".

The patch also fixes poor arsup.c plugin support.

bfd/
	* plugin.c (plugin_vec): Remove archive support.
	* configure.ac: Remove plugin archive warning, and don't disable
	plugins by default on anything but aout targets.
	* configure: Regenerate.
binutils/
	* bucomm.h (set_plugin_target): New inline function.
	* ar.c: Remove unneeded forward declarations.
	(open_inarch): Don't use "plugin" if defaulting target when
	opening an archive, use "plugin" when opening elements.
	(replace_members): Use "plugin" when opening replacement or
	additional elements.
	* arsup.c: Remove unneeded forward declarations.
	(plugin_target): New.
	(ar_open): Don't open archives using "plugin", use it when
	opening elements.
	(ar_addmod): Use plugin_target.
	(ar_replace): Use plugin_target when opening replacement or
	additional elements.
	(ar_extract): Don't bfd_openr.
	* nm.c (display_archive): Open archive elements using the
	"plugin" target.