crush: clean up types, const-ness

Move various types from int -> __u32 (or similar), and add const as
appropriate.

This reflects changes that have been present in the userland implementation
for some time.

Reviewed-by: Alex Elder <elder@inktank.com>
Signed-off-by: Sage Weil <sage@inktank.com>

include/linux/crush/mapper.h

@@ -10,11 +10,11 @@
 
 #include "crush.h"
 
-extern int crush_find_rule(struct crush_map *map, int pool, int type, int size);
-extern int crush_do_rule(struct crush_map *map,
+extern int crush_find_rule(const struct crush_map *map, int ruleset, int type, int size);
+extern int crush_do_rule(const struct crush_map *map,
 			 int ruleno,
 			 int x, int *result, int result_max,
 			 int forcefeed,    /* -1 for none */
-			 __u32 *weights);
+			 const __u32 *weights);
 
 #endif