Fix several old bugs which got worse over time:

o WARNS should be WARNS?= (broke in rev 1.21).
o Includes should be sorted.
o Move "mntopt.h" out of the standard includes section.
o Rewrite usage() to match the manual page and make it < 80 characters.
o Remove extra .El call on line 187.  It is unused and causes mdoc(7) warnings.

Discussed with:	bde

sbin/mount_msdosfs/Makefile

@@ -10,7 +10,7 @@ LDADD=	-lkiconv
 
 MOUNT=	${.CURDIR}/../mount
 CFLAGS+= -I${MOUNT}
-WARNS=	2
+WARNS?=	2
 
 # Needs to be dynamically linked for optional dlopen() access to
 # userland libiconv

sbin/mount_msdosfs/mount_msdosfs.8

@@ -184,7 +184,6 @@ To mount a Japanese msdos file system located in /dev/ad1s1:
 .Bd -literal -offset indent
 # mount_msdosfs -L ja_JP.eucJP -D CP932 /dev/ad1s1 /mnt
 .Ed
-.El
 .Sh SEE ALSO
 .Xr mount 2 ,
 .Xr unmount 2 ,

sbin/mount_msdosfs/mount_msdosfs.c

@@ -38,9 +38,9 @@ static const char rcsid[] =
 #include <sys/param.h>
 #include <sys/mount.h>
 #include <sys/stat.h>
-#include <sys/module.h>
 #include <sys/iconv.h>
 #include <sys/linker.h>
+#include <sys/module.h>
 
 #include <fs/msdosfs/msdosfsmount.h>
 
@@ -56,6 +56,7 @@ static const char rcsid[] =
 #include <string.h>
 #include <sysexits.h>
 #include <unistd.h>
+
 #include "mntopts.h"
 
 #define TRANSITION_PERIOD_HACK
@@ -312,13 +313,14 @@ usage()
 {
 #ifdef TRANSITION_PERIOD_HACK
 	fprintf(stderr, "%s\n%s\n%s\n",
-	"usage: mount_msdosfs [-o options] [-u user] [-g group] [-m mask] [-M mask]",
-	"                     [-s] [-l] [-9] [-L locale] [-D dos-codepage] [-W table]",
-	"                     bdev dir");
+	"usage: mount_msdosfs [-9ls] [-D DOS_codepage] [-g gid] [-L locale]",
+	"                     [-M mask] [-m mask] [-o options] [-u uid]",
+	"		      [-W table] special node");
 #else
-	fprintf(stderr, "%s\n%s\n",
-	"usage: mount_msdosfs [-o options] [-u user] [-g group] [-m mask] [-M mask]",
-	"                     [-s] [-l] [-9] [-L locale] [-D dos-codepage] bdev dir");
+	fprintf(stderr, "%s\n%s\n%s\n",
+	"usage: mount_msdosfs [-9ls] [-D DOS_codepage] [-g gid] [-L locale]",
+	"                     [-M mask] [-m mask] [-o options] [-u uid]",
+	"		      special node");
 #endif
 	exit(EX_USAGE);
 }