A number of cleanups. Now compiles with libc5, glibc, and uClibc. Fix a few

shadowed variables.  Move (almost) all syscalls to libbb/syscalls.c, so I can
handle them sanely and all at once.
 -Erik

networking/tftp.c

@@ -116,7 +116,7 @@ static inline int tftp(int cmd, struct hostent *host,
 	len = sizeof(sa);
 
 	memset(&sa, 0, len);
-	bind(socketfd, &sa, len);
+	bind(socketfd, (struct sockaddr *)&sa, len);
 
 	sa.sin_family = host->h_addrtype;
 	sa.sin_port = htons(port);