* gdb_ptrace.h (PT_TRACE_ME): Define to zero if not already

* gdb_ptrace.h (PT_TRACE_ME): Define to zero if not already
defined.
* inf-ptrace.c: Tweak comments.
(inf_ptrace_me): Use PT_TRACE_ME instead of hardcoded zero.
(inf_ptrace_mourn_inferior): Call waitpid.
(inf_ptrace_attach): Use pid_t, Remove unnecessary cast.
(inf_ptrace_detach): Use pid_t.  Use ptid_get_pid instead of
PIDGET.
(inf_ptrace_kill): Rename from inf_ptrace_kill_inferior.  Use
pid_t.  Use ptid_get_pid instead of PIDGET.
(inf_ptrace_kill): Call waitpid instead of wait.
(inf_ptrace_resume): Use pid_t.  Use ptid_get_pid instead of
PIDGET.
(inf_ptrace_wait): Use waitpid instead wait.  Use pid_t.  Don't
call target_has_exited or target_thread_alive.  Properly ignore
terminated detached child processes.
(inf_ptrace_has_exited): Remove function.
(inf_ptrace_xfer_partial): Use pid_t.  Use ptid_get_pid instead of
PIDGET.  Use gdb_byte instead of `unsigned char'.
(inf_ptrace_thread_alive): Use ptid_get_pid instead of PIDGET.
(inf_ptrace_pid_to_str): Remove function.
(inf_ptrace_target): Use inf_ptrace_kill instead of
inf_ptrace_kill_inferior.  Use normal_pid_to_str instead of
inf_ptrace_pid_to_str.  Don't set to_has_exited.
(inf_ptrace_fetch_register, inf_ptrace_store_register): Reformat
long lines.