* solib-svr4.c: Include observer.h.

	* solib-svr4.c: Include observer.h.
	(debug_base, debug_loader_offset_p, debug_loader_offset)
	(debug_loader_name, main_lm_addr): Move these globals...
	(struct svr4_info): ... into this new structure.
	(svr4_info_p): New typedef.
	(svr4_info): New global.
	(get_svr4_info, remove_svr4_info, solib_svr4_inferior_exit): New
	functions.
	(locate_base, solib_svr4_r_map, solib_svr4_r_brk)
	(solib_svr4_r_ldsomap): Add svr4_info argument.  Adjust to
	per-inferior svr4.
	(open_symbol_file_object): Adjust to per-inferior svr4.
	(svr4_default_sos, svr4_current_sos, svr4_fetch_objfile_link_map):
	Ditto.
	(enable_break): Add svr4_info argument.  Adjust to per-inferior
	svr4.
	(enable_break, svr4_solib_create_inferior_hook, svr4_clear_solib):
	Adjust to per-inferior svr4.
	(_initialize_svr4_solib): Install the solib_svr4_inferior_exit
	observer.