hook close() to prevent rude programs like ssh to close our pipes

those pipes are needed to talk with the dns-name allocator thread.

closes #9

src/core.h

@@ -82,6 +82,7 @@ int connect_proxy_chain (int sock, ip_type target_ip, unsigned short target_port
 
 void proxychains_write_log(char *str, ...);
 
+typedef int (*close_t)(int);
 typedef int (*connect_t)(int, const struct sockaddr *, socklen_t);
 typedef struct hostent* (*gethostbyname_t)(const char *);
 typedef int (*freeaddrinfo_t)(struct addrinfo *);