libav: added missing marker function
libav: make sure we don't write a trailer if the header has not been written
libav: cosmetics
libav: print warning if bitstream filter fails
libav: fixed minor memory leak when errors accurs.
libav: drop h264 packets when bitstream filter fails
Fix #1643 - dvb: alter the way we handle dvb tuning

This ensures that demux filters are not installed until after tuning
is locked. This should resolve most stale data issues.
support: remove confusing (and uncessary) default values.
gtimer: increased resolution of the gtimer system.

This is needed to resolve a dvb tuner deadlock issued caused by my
re-jigging of the tuning setup code.
Fix #1666 - dvb: rework the adapter tuning to stop possible deadlock
Fix #1674 - remove spurious (info) log message before daemon().
support: some updates to build system
gtimer: fix live lock problem caused by wrong clock usage
dvb: demux setup code went missing!