fix a serious bug in libproc's proc_attach

proc_attach always frees any struct proc_handle data
that it allocates, but that is supposed to be done
only in error conditions.

PR:		bin/158431
Approved by:	re (kib)
MFC after:	1 week

lib/libproc/proc_create.c

@@ -79,12 +79,11 @@ proc_attach(pid_t pid, int flags, struct proc_handle **pphdl)
 	else
 		phdl->status = PS_STOP;
 
+out:
 	if (error)
 		proc_free(phdl);
 	else
 		*pphdl = phdl;
-out:
-	proc_free(phdl);
 	return (error);
 }