kdump: nicer printing of wait*() ID arguments

Currently, both of these will print pid/uid/gid/sid/jid in hex, which
isn't very helpful for eyeballing.  Align more closely with truss(1) and
print these in decimal instead.

`ip` is likely wider than our ID type, so we do a small casting trick in
wait4(2) to get it sign-extended and rendered properly.

Reviewed by:	markj
Differential Revision:	https://reviews.freebsd.org/D50496

usr.bin/kdump/kdump.c

@@ -937,7 +937,8 @@ ktrsyscall_freebsd(struct ktr_syscall *ktr, register_t **resip,
 				narg -= 2;
 				break;
 			case SYS_wait4:
-				print_number(ip, narg, c);
+				*ip = (pid_t)*ip;
+				print_decimal_number(ip, narg, c);
 				print_number(ip, narg, c);
 				putchar(',');
 				print_mask_arg0(sysdecode_wait4_options, *ip);
@@ -950,7 +951,7 @@ ktrsyscall_freebsd(struct ktr_syscall *ktr, register_t **resip,
 				c = ',';
 				ip++;
 				narg--;
-				print_number64(first, ip, narg, c);
+				print_decimal_number64(first, ip, narg, c);
 				print_number(ip, narg, c);
 				putchar(',');
 				print_mask_arg(sysdecode_wait6_options, *ip);