livehttp: gather blocks so we can write more at the time
livehttp: gather blocks so we can write more at the time

Otherwise we would loop and write() ts-packet at a time.

(cherry picked from commit 609a5fe2b4cdd2cca8bdd99e917ddd4d377bc6e6)
Signed-off-by: Ilkka Ollakka <88b345e2e0969920adc1eaa21d1a29b223865bcf@videolan.org>

jomanmuk/vlc-2.2,jomanmuk/vlc-2.2,jomanmuk/vlc-2.2,jomanmuk/vlc-2.2,jomanmuk/vlc-2.2,jomanmuk/vlc-2.2,jomanmuk/vlc-2.2