fix cast for some systems which are broken due to absense of socklen_t,...

fix cast for some systems which are broken due to absense of socklen_t, therefore now use curl_socklen_t.

lib/inet_ntop.h

@@ -31,7 +31,8 @@ char *Curl_inet_ntop(int af, const void *addr, char *buf, size_t size);
 #ifdef HAVE_ARPA_INET_H
 #include <arpa/inet.h>
 #endif
-#define Curl_inet_ntop(af,addr,buf,size) inet_ntop(af,addr,buf,(socklen_t)size)
+#define Curl_inet_ntop(af,addr,buf,size) \
+        inet_ntop(af,addr,buf,(curl_socklen_t)size)
 #endif
 
 #endif /* __INET_NTOP_H */