add helper macro to determine the LwIP error code for the current task

lwip/src/include/arch/cc.h

@@ -81,5 +81,5 @@ typedef size_t mem_ptr_t;
 
 #define LWIP_PLATFORM_ASSERT(x) do {kprintf("Assertion \"%s\" failed at line %d in %s\n", \
                                      x, __LINE__, __FILE__); abort();} while(0)
-				     
+
 #endif /* __ARCH_CC_H__ */

lwip/src/include/arch/sys_arch.h

@@ -43,4 +43,10 @@ static inline void sys_arch_unprotect(sys_prot_t pval)
 #endif
 #endif
 
+/* define errno to determine error code */
+#ifdef CONFIG_LWIP
+#define ERRNO
+#define errno per_core(current_task)->lwip_err
+#endif
+
 #endif /* __ARCH_SYS_ARCH_H__ */