Remove the attach_flag global, and make it per-inferior.

	Remove the attach_flag global, and make it per-inferior.

	* inferior.h (attach_flag): Delete.
	(inferior_process): Declare.
	* solib.c (update_solib_list): Adjust.
	* gnu-nat.c (gnu_create_inferior, gnu_attach): Adjust.
	* inf-ptrace.c (inf_ptrace_detach): Adjust.
	(inf_ptrace_files_info): Get it from the current inferior.
	* inf-ttrace.c (inf_ttrace_attach): Adjust.
	(inf_ttrace_files_info): Get it from the current
	inferior.
	* inflow.c (terminal_inferior, terminal_ours_1, set_sigint_trap)
	(clear_sigint_trap): Get it from the current process.
	* remote.c (extended_remote_attach_1)
	(extended_remote_create_inferior_1): Adjust.
	* top.c (quit_confirm, quit_target): Get it from the current inferior.
	* procfs.c (do_detach): Adjust.
	(procfs_wait): Get it from the event inferior.
	(procfs_files_info): Get it from the current inferior.
	* nto-procfs.c (procfs_files_info): Likewise.
	(procfs_attach): Adjust.  Set the attach_flag here.
	(do_attach): Don't set it here.
	(procfs_detach): Don't clear it.
	(procfs_mourn_inferior): Don't clear it.
	* solib-osf.c (osf_solib_create_inferior_hook): Adjust.
	* target.c (attach_flag): Delete.
	(generic_mourn_inferior): Don't clear it.
	* win32-nat.c (get_win32_debug_event): Get it from the event
	process.
	(do_initial_win32_stuff): Add attaching argument.  Set attach_flag
	in the inferior accordingly.
	(win32_attach): Don't set the attach_flag here.  Pass 1 to
	do_intial_win32_stuff.
	(win32_files_info): Get it from the current inferior.
	(win32_create_inferior): Dont clear attach_flag here.  Pass 0 to
	do_intial_win32_stuff.