libobs: Fix missing include due to FFmpeg 5 changes

Since [1], avcodec/version.h is not included anymore in codec.h and
therefore is not included any more  in avformat.h.
As a result, LIBAVCODEC_VERSION_INT is no longer defined. This commit
fixes the include.
Since obviously we can't ifdef the avcodec include by referring to an
avcodec version, we ifdef it with the avformat version which was bumped
at the same time [2].

[1] libavcodec: Split version.h
https://github.com/FFmpeg/FFmpeg/commit/f2da2e1458b76a1d6c068673430b46cf2850bc51
[2] doc: Add an entry to APIchanges about changes to version.h and
 version_major.h
https://github.com/FFmpeg/FFmpeg/commit/f3a0e2ee2b97e2d46b351c29853c056d126884e2

Signed-off-by: pkv <[email protected]>

libobs/media-io/media-remux.c

@@ -22,7 +22,9 @@
 #include "../util/platform.h"
 
 #include <libavformat/avformat.h>
-
+#if LIBAVFORMAT_VERSION_INT >= AV_VERSION_INT(59, 20, 100)
+#include <libavcodec/version.h>
+#endif
 #include <sys/types.h>
 #include <sys/stat.h>