Group errors for many missing shared libraries.

	Group errors for many missing shared libraries.

	* solist.h (struct so_list): Remove from_tty.
	* solib.c (solib_bfd_open): Return NULL if we failed to open a BFD.
	(solib_map_sections): Take so_list argument.  Return 0 if we
	failed to open a BFD.  Add target sections here.
	(symbol_add_stub): Delete.
	(solib_read_symbols): Inline symbol_add_stub.  Use current flags,
	not from_tty copied from the so_list.  Don't warn a second time
	for a missing library.
	(update_solib_list): Don't save from_tty.  Use TRY_CATCH.  Do not
	add to the section table here.  Print out a single warning for all
	missing libraries.
	* bsd-uthread.c (bsd_uthread_solib_loaded): Always pass 0 for
	flags.