* solist.h (struct target_so_ops): New member bfd_open.

	* solist.h (struct target_so_ops): New member bfd_open.
	(solib_find): Add prototype.
	(solib_bfd_fopen): Add prototype.
	* solib.c (solib_find, solib_bfd_fopen): New functions, extracted
	from solib_bfd_open.
	(solib_bfd_open): Use ops->bfd_open override if present.  Call
	solib_find and solib_bfd_open otherwise.

	* objfiles.h (OBJF_KEEPBFD): New define.
	* objfiles.c (free_objfile): Do not close BFD if OBJF_KEEPBFD
	objfile flag is set.
	* solib.c (symbol_add_stub): Do not allocate second BFD for
	shared library; use OBJF_KEEPBFD flag on solib objfile.