Reduce <sys/disklabel.h> poisoning a bit.

Sponsored by:	DARPA & NAI Labs.

sys/dev/vinum/vinumext.h

@@ -162,6 +162,7 @@ char *basename(char *);
 
 void expand_table(void **, int, int);
 
+struct disklabel;
 struct request;
 struct rqgroup *allocrqg(struct request *rq, int elements);
 void deallocrqg(struct rqgroup *rqg);

sys/dev/vinum/vinumparser.c

@@ -66,7 +66,6 @@
 /* All this mess for a single struct definition */
 #include <sys/uio.h>
 #include <sys/namei.h>
-#include <sys/disklabel.h>
 #include <sys/mount.h>
 
 #include <dev/vinum/vinumvar.h>