* util/hostdisk.c [__FreeBSD__ || __FreeBSD_kernel__]: Include
<sys/param.h> and <sys/sysctl.h>.
(open_device) [__FreeBSD__ || __FreeBSD_kernel_]: Use sysctlgetbyname()
to add 0x10 to `kern.geom.debugflags' if it's not already set, before
opening the device and reset them afterwards.