hlsenc: Add a proper dependency on the mpegts muxer

The hls muxer itself doesn't have any direct (object file level)
dependencies on mpegtsenc.o, and including that object file
directly doesn't ensure that it is registered so that the muxer
actually is accessible.

Signed-off-by: Martin Storsjö <martin@martin.st>
hlsenc: Append the last incomplete segment when closing the output

Also avoid comparing NOPTS values.

Bug-id: 551
Signed-off-by: Martin Storsjö <martin@martin.st>
hlsenc: Don't reset the number variable when wrapping

The counter itself shouldn't be wrapped, since it is used for
determining end_pts for the next segment - only wrap the number
used for the segment file name.

Signed-off-by: Martin Storsjö <martin@martin.st>