Convert ff_is_multicast_address to take a struct sockaddr parameter

Not all users of this function will have a full struct sockaddr_storage
available, and casting other sockaddrs to sockaddr_storage is wrong,
while any sockaddr can be cast to a base sockaddr.

Originally committed as revision 25388 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavformat/network.h

@@ -162,13 +162,13 @@ const char *ff_gai_strerror(int ecode);
 #define IN6_IS_ADDR_MULTICAST(a) (((uint8_t *) (a))[0] == 0xff)
 #endif
 
-static inline int ff_is_multicast_address(struct sockaddr_storage *addr)
+static inline int ff_is_multicast_address(struct sockaddr *addr)
 {
-    if (addr->ss_family == AF_INET) {
+    if (addr->sa_family == AF_INET) {
         return IN_MULTICAST(ntohl(((struct sockaddr_in *)addr)->sin_addr.s_addr));
     }
 #if HAVE_STRUCT_SOCKADDR_IN6
-    if (addr->ss_family == AF_INET6) {
+    if (addr->sa_family == AF_INET6) {
         return IN6_IS_ADDR_MULTICAST(&((struct sockaddr_in6 *)addr)->sin6_addr);
     }
 #endif

libavformat/udp.c

@@ -254,7 +254,7 @@ int udp_set_remote_url(URLContext *h, const char *uri)
     if (s->dest_addr_len < 0) {
         return AVERROR(EIO);
     }
-    s->is_multicast = ff_is_multicast_address(&s->dest_addr);
+    s->is_multicast = ff_is_multicast_address((struct sockaddr*) &s->dest_addr);
 
     return 0;
 }