[libmicrohttpd] Clarification on receiving on one thread, replying on another

[Tom Cornell]

Quick question, probably: Should I be able to send replies from a different 
thread from the one that runs the access handler callback, using internal 
select? (Using suspend/resume. Also this is 0.9.50, in case that matters.)

I am getting a panic from the very end of build_header_response (I think line 
1123 in 0.9.50). From my own logs (and custom panic function), it looks like 
mhd_panic is called by the main listener thread, pretty much right after my 
worker thread has sent the response. Usually, things (appear to) work fine for 
a few minutes before the panic, but I am assuming that is more a matter of luck 
than design.

I know I could be doing this with external select. This is mainly out of 
curiosity to know whether I really am going against the grain of MHD's design 
here, or if instead I've  just overlooked something I should/should not be 
doing. If this is something that should work, then I can go into more detail 
about what I am doing/trying to do.

Tom Cornell