FreeBSD: minor_t needs to be signed so that -1 is recognized as such

zfsdev_close sets zs_minor to -1 to avoid duplicate calls to
destroy. This doesn't mix well with the current u_int used.

Reviewed-by: Brian Behlendorf <[email protected]>
Reviewed-by: Alexander Motin <[email protected]>
Signed-off-by: Matt Macy <[email protected]>
Closes #11437

Author: mattmacy

include/os/freebsd/spl/sys/types.h

@@ -64,7 +64,7 @@ typedef u_int		uint_t;
 typedef u_char		uchar_t;
 typedef u_short		ushort_t;
 typedef u_long		ulong_t;
-typedef	u_int		minor_t;
+typedef	int		minor_t;
 /* END CSTYLED */
 #ifndef	_OFF64_T_DECLARED
 #define	_OFF64_T_DECLARED