lavf/os_support: Only compile inet_aton() if getaddrinfo() is needed.

Silences a warning:
libavformat/os_support.c:49:12: warning: 'inet_aton' defined but not used

Reported-by: Reino Wijnsma

libavformat/os_support.c

@@ -43,6 +43,7 @@
 
 #include "network.h"
 
+#if !HAVE_GETADDRINFO
 #if !HAVE_INET_ATON
 #include <stdlib.h>
 
@@ -62,7 +63,6 @@ static int inet_aton(const char *str, struct in_addr *add)
 }
 #endif /* !HAVE_INET_ATON */
 
-#if !HAVE_GETADDRINFO
 int ff_getaddrinfo(const char *node, const char *service,
                    const struct addrinfo *hints, struct addrinfo **res)
 {