httplive: Adjust conditions for playlist reloading

Commit 7655d6c889d2425c1fd4615f7e2692df1a47470c changes HLS http
playlist reloading policy. But leaving only one fragment in buffer is
not enough. This patch ensures that less than three fragments in buffer
leads to playlist reloading. The overal result is more reliable http
streams.

Signed-off-by: Ilkka Ollakka <ileoo@videolan.org>
auhal: fail in render callbacks if bytesToCopy is <= 0

This should not happen in the current implementation.
src: darwin/thread: reimplement monotonic clock for darwin

This is based on code which was silently removed in
0f9a94f2183fc6c6e9ce8b77eb497aab160cbbbd and
45c2bc0811cc2d9fe8e11448a05742d7ff6da1d8.

The patch solves timing issues if the user changes the system time, for
instance while playback.

Another timing issue was pointed out if vlc_cond_init_with_daytime is used.
This remains unfixed, and is documented in a Fixme.

close #10072
src: darwin/thread: do not create own condattr
Merge remote-tracking branch: upstream/master