fix fd leak (missing close-on-exec) in getifaddrs

src/network/getifaddrs.c

@@ -66,7 +66,7 @@ static void ipv6netmask(unsigned prefix_length, struct sockaddr_in6 *sa)
 
 static void dealwithipv6(stor **list, stor** head)
 {
-	FILE* f = fopen("/proc/net/if_inet6", "r");
+	FILE* f = fopen("/proc/net/if_inet6", "rbe");
 	/* 00000000000000000000000000000001 01 80 10 80 lo
 	   A                                B  C  D  E  F
 	   all numbers in hex