i386-moss and i386-openbsd ld config

i386-moss and i386-openbsd ld config

i386-moss is an ELF target needing ldelf.c.  x86 openbsd wouldn't even
build, so I added entries to do the same as netbsd.  Quite likely this
isn't ideal but if the openbsd folk don't contribute their changes
this is what they get.

	* configure.tgt (i[3-7]86-*-moss*): Don't clear targ_extra_ofiles.
	(i[3-7]86-*-openbsd*, x86_64-*-openbsd*): Add.