HTTP FLV Live Stream triggers edge to pull content from origin

[winlinvip]

https://github.com/winlinvip/simple-rtmp-server/issues/324

TRANS_BY_GPT3

[winlinvip]

hstrs, this configuration needs to be enabled in SRS2. In SRS3, it is enabled by default, so ignore this configuration.

TRANS_BY_GPT3

[winlinvip]

HSTRS is http flv trigger rtmp fetching data from upstream. When user play the http-flv on edge SRS, it will fetch data from upstream over RTMP, like the RTMP edge.