sockets.c Remove "#include <errno.h>" from sockets.c to avoid multiple

definition of macros (in errno.h and lwip/arch.h) if LWIP_PROVIDE_ERRNO is
    defined. This is the way it should have been already (looking at
    doc/sys_arch.txt)

src/api/sockets.c

@@ -33,7 +33,6 @@
  */
 
 #include <string.h>
-#include <errno.h>
 
 #include "lwip/opt.h"
 #include "lwip/api.h"