os_support: make poll() fallbacks conditional on CONFIG_NETWORK

poll() is only used by networking code, so the fallback should
only be built if networking is enabled.  Also remove CONFIG_FFSERVER
condition from the declarations.

This should fix building on systems without poll(), broken
by a8475bbdb6.

Signed-off-by: Mans Rullgard <mans@mansr.com>
(cherry picked from commit 362d8f7d9e)

libavformat/os_support.c

@@ -234,7 +234,6 @@ int ff_socket_nonblock(int socket, int enable)
       return fcntl(socket, F_SETFL, fcntl(socket, F_GETFL) & ~O_NONBLOCK);
 #endif
 }
-#endif /* CONFIG_NETWORK */
 
 #if !HAVE_POLL_H
 int poll(struct pollfd *fds, nfds_t numfds, int timeout)
@@ -304,3 +303,4 @@ int poll(struct pollfd *fds, nfds_t numfds, int timeout)
     return rc;
 }
 #endif /* HAVE_POLL_H */
+#endif /* CONFIG_NETWORK */

libavformat/os_support.h

@@ -55,7 +55,6 @@ typedef int socklen_t;
 #define closesocket close
 #endif
 
-#if CONFIG_FFSERVER
 #if !HAVE_POLL_H
 typedef unsigned long nfds_t;
 
@@ -82,7 +81,6 @@ struct pollfd {
 
 int poll(struct pollfd *fds, nfds_t numfds, int timeout);
 #endif /* HAVE_POLL_H */
-#endif /* CONFIG_FFSERVER */
 #endif /* CONFIG_NETWORK */
 
 #endif /* AVFORMAT_OS_SUPPORT_H */