avformat/http: include version.h

This is needed to get LIBAVFORMAT_VERSION, used as part of the user agent.
Fixes a recent regression.

Reviewed-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
Signed-off-by: James Almer <jamrial@gmail.com>

libavformat/http.c

@@ -41,6 +41,7 @@
 #include "network.h"
 #include "os_support.h"
 #include "url.h"
+#include "version.h"
 
 /* XXX: POST protocol is not completely implemented because ffmpeg uses
  * only a subset of it. */