Add a handy macro to represent null mount option, MOPT_NULL, and make

use of the macro in sbin/mount*'s, by replacing:

	mopts[] = {
	    MOPT_STDOPTS,
	    { NULL }
	}

With:
	mopts[] = {
	    MOPT_STDOPTS,
	    MOPT_NULL
	}

This change will help to reduce the situation that we don't explicitly
initialize "struct mntopt"'s.  It should not contribute to any
functional/logical changes as far as I can tell.

sbin/mount/mntopts.h

@@ -65,6 +65,9 @@ struct mntopt {
 /* This is parsed by mount(8), but is ignored by specific mount_*(8)s. */
 #define MOPT_AUTO		{ "auto",	0, 0, 0 }
 
+/* A handy macro as terminator of MNT_ array */
+#define MOPT_NULL		{ NULL,		0, 0, 0 }
+
 #define MOPT_FSTAB_COMPAT						\
 	MOPT_RO,							\
 	MOPT_RW,							\

sbin/mount/mount_ufs.c

@@ -64,7 +64,7 @@ static struct mntopt mopts[] = {
 	MOPT_SYNC,
 	MOPT_UPDATE,
 	MOPT_SNAPSHOT,
-	{ NULL }
+	MOPT_NULL
 };
 
 int

sbin/mount_cd9660/mount_cd9660.c

@@ -77,7 +77,7 @@ struct mntopt mopts[] = {
 	{ "rrip", 1, ISOFSMNT_NORRIP, 1 },
 	{ "joliet", 1, ISOFSMNT_NOJOLIET, 1 },
 	{ "strictjoliet", 1, ISOFSMNT_BROKENJOLIET, 1 },
-	{ NULL }
+	MOPT_NULL
 };
 
 int	get_ssector(const char *dev);

sbin/mount_ext2fs/mount_ext2fs.c

@@ -60,7 +60,7 @@ struct mntopt mopts[] = {
 	MOPT_FORCE,
 	MOPT_SYNC,
 	MOPT_UPDATE,
-	{ NULL }
+	MOPT_NULL
 };
 
 static void	usage(void) __dead2;

sbin/mount_hpfs/mount_hpfs.c

@@ -50,7 +50,7 @@
 
 static struct mntopt mopts[] = {
 	MOPT_STDOPTS,
-	{ NULL }
+	MOPT_NULL
 };
 
 static gid_t	a_gid(char *);

sbin/mount_msdosfs/mount_msdosfs.c

@@ -73,7 +73,7 @@ static struct mntopt mopts[] = {
 	{ "shortnames", 0, MSDOSFSMNT_SHORTNAME, 1 },
 	{ "longnames", 0, MSDOSFSMNT_LONGNAME, 1 },
 	{ "nowin95", 0, MSDOSFSMNT_NOWIN95, 1 },
-	{ NULL }
+	MOPT_NULL
 };
 
 static gid_t	a_gid(char *);

sbin/mount_nfs/mount_nfs.c

@@ -121,7 +121,7 @@ struct mntopt mopts[] = {
 	{ "lockd", 1, ALTF_NOLOCKD, 1 },
 	{ "inet4", 1, ALTF_NOINET4, 1 },
 	{ "inet6", 1, ALTF_NOINET6, 1 },
-	{ NULL }
+	MOPT_NULL
 };
 
 struct nfs_args nfsdefargs = {

sbin/mount_nfs4/mount_nfs4.c

@@ -151,7 +151,7 @@ struct mntopt mopts[] = {
 	{ "lockd", 1, ALTF_NOLOCKD, 1 },
 	{ "inet4", 1, ALTF_NOINET4, 1 },
 	{ "inet6", 1, ALTF_NOINET6, 1 },
-	{ NULL }
+	MOPT_NULL
 };
 
 struct nfs_args nfsdefargs = {

sbin/mount_ntfs/mount_ntfs.c

@@ -58,7 +58,7 @@
 
 static struct mntopt mopts[] = {
 	MOPT_STDOPTS,
-	{ NULL }
+	MOPT_NULL
 };
 
 static gid_t	a_gid(char *);

sbin/mount_nullfs/mount_nullfs.c

@@ -59,7 +59,7 @@ static const char rcsid[] =
 
 struct mntopt mopts[] = {
 	MOPT_STDOPTS,
-	{ NULL }
+	MOPT_NULL
 };
 
 int	subdir(const char *, const char *);

sbin/mount_reiserfs/mount_reiserfs.c

@@ -41,7 +41,7 @@
 
 struct mntopt mopts[] = {
 	MOPT_STDOPTS,
-	{ NULL }
+	MOPT_NULL
 };
 
 void	usage(void);

sbin/mount_std/mount_std.c

@@ -59,7 +59,7 @@ static const char rcsid[] =
 
 static struct mntopt mopts[] = {
 	MOPT_STDOPTS,
-	{ NULL }
+	MOPT_NULL
 };
 
 static char *fsname;

sbin/mount_udf/mount_udf.c

@@ -64,7 +64,7 @@
 struct mntopt mopts[] = {
 	MOPT_STDOPTS,
 	MOPT_UPDATE,
-	{ NULL, 0, 0, 0 }
+	MOPT_NULL
 };
 
 int	set_charset(char **, char **, const char *);

sbin/mount_ufs/mount_ufs.c

@@ -61,7 +61,7 @@ struct mntopt mopts[] = {
 	MOPT_SYNC,
 	MOPT_UPDATE,
 	MOPT_SNAPSHOT,
-	{ NULL }
+	MOPT_NULL
 };
 
 void	usage(void);

sbin/mount_umapfs/mount_umapfs.c

@@ -79,7 +79,7 @@ static const char rcsid[] =
 
 static struct mntopt mopts[] = {
 	MOPT_STDOPTS,
-	{ NULL }
+	MOPT_NULL
 };
 
 static void	usage(void) __dead2;

sbin/mount_unionfs/mount_unionfs.c

@@ -60,7 +60,7 @@ static const char rcsid[] =
 
 static struct mntopt mopts[] = {
 	MOPT_STDOPTS,
-	{ NULL }
+	MOPT_NULL
 };
 
 static int	subdir(const char *, const char *);