Move bfd_alloc, bfd_zalloc and bfd_release to libbfd.c

These functions don't belong in opncls.c.

	* libbfd-in.h (bfd_release): Delete prototype.
	* opncls.c (bfd_alloc, bfd_zalloc, bfd_release): Move to..
	* libbfd.c: ..here.  Include objalloc.c and provide bfd_release
	with a FUNCTION comment.
	* bfd-in2.h: Regenerate.
	* libbfd.h: Regenerate.