when recvfrom prototype uses a void pointer for arguments 2, 5 or 6 this will

now cause the definition of RECVFROM_TYPE_ARG2_IS_VOID, RECVFROM_TYPE_ARG5_IS_VOID
or RECVFROM_TYPE_ARG6_IS_VOID, as appropriate.

lib/config.dos

@@ -86,6 +86,7 @@
 #define RECVFROM_TYPE_ARG5     struct sockaddr
 #define RECVFROM_TYPE_ARG6     int
 #define RECVFROM_TYPE_RETV     int
+#define RECVFROM_TYPE_ARG2_IS_VOID 1
 
 #define BSD