Change capabilities to uint64_t

- Since the capabilities are a bitmask, it is better if an unsigned
  integral type is used.
- Since the function is part of an ABI, it is better if an explicit
  size is used.
- 64-bits so that there also is room for independent filter
  capabilities.

server/modules/routing/readconnroute/readconnection.h

@@ -59,7 +59,6 @@ typedef struct router_client_session
     DCB *backend_dcb; /*< DCB Connection to the backend      */
     DCB *client_dcb; /**< Client DCB */
     struct router_client_session *next;
-    int rses_capabilities; /*< input type, for example */
 #if defined(SS_DEBUG)
     skygw_chk_t rses_chk_tail;
 #endif