* linux-i386-low.c (ps_get_thread_area): New.

	* linux-i386-low.c (ps_get_thread_area): New.
	* linux-x86-64-low.c (ps_get_thread_area): New.
	* linux-low.c: Include <sys/syscall.h>.
	(linux_kill_one_process): Don't kill the first thread here.
	(linux_kill): Kill the first thread here.
	(kill_lwp): New function.
	(send_sigstop, linux_send_signal): Use it.
	* proc-service.c: Clean up #ifdefs.
	(fpregset_info): Delete.
	(ps_lgetregs): Update and enable implementation.
	(ps_lsetregs, ps_lgetfpregs, ps_lsetfpregs): Remove disabled
	implementations.
	* remote-utils.c (struct sym_cache, symbol_cache): New.
	(input_interrupt): Print a clearer message.
	(async_io_enabled): New variable.
	(enable_async_io, disable_async_io): Use it.  Update comments.
	(look_up_one_symbol): Use the symbol cache.
	* thread-db.c (thread_db_look_up_symbols): New function.
	(thread_db_init): Update comments.  Call thread_db_look_up_symbols.