table: remove inclusion of mbuf header

The rte_table header file includes the mbuf header file, but it does not
need to do so as it only uses pointers to the struct rte_mbuf type, and
does not use any of the mbuf internals, nor any of the mbuf functions or
macros. Therefore the inclusion is unnecessary, and can be replaced by a
forward declaration of the mbuf type.

Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>
Acked-by: Olivier Matz <olivier.matz@6wind.com>

lib/librte_table/rte_table.h

@@ -55,9 +55,10 @@ extern "C" {
  ***/
 
 #include <stdint.h>
-#include <rte_mbuf.h>
 #include <rte_port.h>
 
+struct rte_mbuf;
+
 /**
  * Lookup table create
  *