libavformat/rtspdec: Don't send teardown if rtsp_hd_out is null

avcodec/vaapi_h264: skip decode if pic has no slices

This fixes / workarounds https://bugs.freedesktop.org/show_bug.cgi?id=105368.
It was hit frequently when watching h264 channels received via DVB-X.
Corresponding kodi bug: xbmc/xbmc#15704

only check for a git rev if the src tree is in a git repo

fixes the version string when building from the kodi depends src tree

only check for a git rev if the src tree is in a git repo

fixes the version string when building from the kodi depends src tree