h1: handle LRS_FLUSHING_BEFORE_CLOSE at ops read
h1: handle LRS_FLUSHING_BEFORE_CLOSE at ops read

read has a tight leash on the states it's happy to turn up there,
it's good to be like that but it turns out LRS_FLUSHING_BEFORE_CLOSE
should be whitelisted since it can happen under some transient
conditions and is valid.

https://github.com/warmcat/libwebsockets/issues/1872
sartura/libwebsockets,sartura/libwebsockets,sartura/libwebsockets,sartura/libwebsockets,sartura/libwebsockets,sartura/libwebsockets,sartura/libwebsockets