netbuf: Move #include "lwip/opt.h" out of #if LWIP_NETCONN || LWIP_SOCKET guard

LWIP_NETCONN and LWIP_SOCKET are defined in opt.h,
so move #include "lwip/opt.h" out of #if LWIP_NETCONN || LWIP_SOCKET guard.

Signed-off-by: Axel Lin <axel.lin@ingics.com>

src/include/lwip/netbuf.h

@@ -32,6 +32,8 @@
 #ifndef LWIP_HDR_NETBUF_H
 #define LWIP_HDR_NETBUF_H
 
+#include "lwip/opt.h"
+
 #if LWIP_NETCONN || LWIP_SOCKET /* don't build if not configured for use in lwipopts.h */
 
 /* don't export the netbuf functions when socket API is enabled but netconn API is disabled */
@@ -41,7 +43,6 @@
 #define LWIP_NETCONN_SCOPE static
 #endif /* LWIP_NETCONN */
 
-#include "lwip/opt.h"
 #include "lwip/pbuf.h"
 #include "lwip/ip_addr.h"
 #include "lwip/ip6_addr.h"