ioctl: assume that all ioctl commands have unsigned int type

In linux, ioctl command number has a 32-bit unsigned integer type:
	fs/ioctl.c:SYSCALL_DEFINE3(ioctl, unsigned int, fd, unsigned int, cmd, unsigned long, arg)
If the kernel completely ignores other bits on 64-bit architectures,
why should strace care?
Let's follow the kernel and treat it as unsigned int.

* defs.h (struct_ioctlent): Change "code" type to "unsigned int".
(ioctl_decode, ioctl_lookup, block_ioctl, loop_ioctl, mtd_ioctl,
ubi_ioctl, ptp_ioctl, scsi_ioctl, sock_ioctl, term_ioctl, rtc_ioctl,
v4l2_ioctl): Likewise.
* ioctl.c (ioctl_decode, ioctl_lookup, compare, ioctl_next_match):
Likewise.
* block.c (block_ioctl): Likewise.
* loop.c (loop_ioctl): Likewise.
* mtd.c (mtd_ioctl, ubi_ioctl): Likewise.
* ptp.c (ptp_ioctl): Likewise.
* scsi.c (scsi_ioctl): Likewise.
* sock.c (sock_ioctl): Likewise.
* term.c (term_ioctl): Likewise.
* time.c (rtc_ioctl): Likewise.
* v4l2.c (v4l2_ioctl): Likewise.
* ioctlsort.c (struct ioctlent, compare, main): Likewise.
diff --git a/sock.c b/sock.c
index 546c651..dfdb10a 100644
--- a/sock.c
+++ b/sock.c
@@ -52,7 +52,7 @@
 }
 
 int
-sock_ioctl(struct tcb *tcp, long code, long arg)
+sock_ioctl(struct tcb *tcp, const unsigned int code, long arg)
 {
 	struct ifreq ifr;
 	struct ifconf ifc;