mpr: Move MAX_INTERFACE_NAME_LEN to mprapi.h and add related constants.

Fix iprtrmib.h so it includes mprapi.h.
diff --git a/include/iprtrmib.h b/include/iprtrmib.h
index 630a54b..ba84cc5 100644
--- a/include/iprtrmib.h
+++ b/include/iprtrmib.h
@@ -18,8 +18,7 @@
 #ifndef WINE_IPRTRMIB_H__
 #define WINE_IPRTRMIB_H__
 
-#define MAX_INTERFACE_NAME_LEN 256
-
+#include <mprapi.h>
 #include <ipifcons.h>
 
 #define MAXLEN_IFDESCR 256