Added a configuration option for slipif for symmetry to loopif (patch #6480)

src/include/lwip/opt.h

@@ -877,6 +877,18 @@
 #define LWIP_HAVE_LOOPIF                0
 #endif
 
+/*
+   ------------------------------------
+   ---------- SLIPIF options ----------
+   ------------------------------------
+*/
+/**
+ * LWIP_HAVE_SLIPIF==1: Support slip interface and slipif.c
+ */
+#ifndef LWIP_HAVE_SLIPIF
+#define LWIP_HAVE_SLIPIF                0
+#endif
+
 /*
    ------------------------------------
    ---------- Thread options ----------

src/netif/slipif.c

@@ -44,6 +44,9 @@
 
 #include "netif/slipif.h"
 #include "lwip/opt.h"
+
+#if LWIP_HAVE_SLIPIF
+
 #include "lwip/def.h"
 #include "lwip/pbuf.h"
 #include "lwip/sys.h"
@@ -273,3 +276,4 @@ slipif_init(struct netif *netif)
   sys_thread_new(SLIPIF_THREAD_NAME, slipif_loop, netif, SLIPIF_THREAD_STACKSIZE, SLIPIF_THREAD_PRIO);
   return ERR_OK;
 }
+#endif /* LWIP_HAVE_SLIPIF */