mknod: correct misplaced -Z description in --help output

* src/mknod.c (usage): Put it after the "Mandatory arguments..." line.

src/mknod.c

@@ -55,12 +55,12 @@ usage (int status)
       fputs (_("\
 Create the special file NAME of the given TYPE.\n\
 \n\
-"), stdout);
-      fputs(_("\
-  -Z, --context=CTX  set the SELinux security context of NAME to CTX\n\
 "), stdout);
       fputs (_("\
 Mandatory arguments to long options are mandatory for short options too.\n\
+"), stdout);
+      fputs(_("\
+  -Z, --context=CTX  set the SELinux security context of NAME to CTX\n\
 "), stdout);
       fputs (_("\
   -m, --mode=MODE   set file permission bits to MODE, not a=rw - umask\n\