unix: add disk ioctl constants for FreeBSD

These ioctls make it possible to obtain information on the geometry of
disk devices, such as their sector size and total size in bytes.

Change-Id: I16449fb1a68b84d266b3fdfda9905cb448676968
GitHub-Last-Rev: 3742e7aec276ffa263fc2dfd6cb3724bb9eda1c0
GitHub-Pull-Request: golang/sys#61
Reviewed-on: https://go-review.googlesource.com/c/sys/+/223537
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Tobias Klauser <tobias.klauser@gmail.com>

unix/mkerrors.sh

@@ -105,6 +105,7 @@ includes_FreeBSD='
 #include <sys/capsicum.h>
 #include <sys/param.h>
 #include <sys/types.h>
+#include <sys/disk.h>
 #include <sys/event.h>
 #include <sys/select.h>
 #include <sys/socket.h>
@@ -493,6 +494,7 @@ ccflags="$@"
 		$2 !~ "RTF_BITS" &&
 		$2 ~ /^(IFF|IFT|NET_RT|RTM(GRP)?|RTF|RTV|RTA|RTAX)_/ ||
 		$2 ~ /^BIOC/ ||
+		$2 ~ /^DIOC/ ||
 		$2 ~ /^RUSAGE_(SELF|CHILDREN|THREAD)/ ||
 		$2 ~ /^RLIMIT_(AS|CORE|CPU|DATA|FSIZE|LOCKS|MEMLOCK|MSGQUEUE|NICE|NOFILE|NPROC|RSS|RTPRIO|RTTIME|SIGPENDING|STACK)|RLIM_INFINITY/ ||
 		$2 ~ /^PRIO_(PROCESS|PGRP|USER)/ ||