Release 4.4.3

[benoitc]

Patch release.

Fixed

• HTTP/2: responses that close the body with a trailing HEADERS frame (trailers) no longer hang the read until recv_timeout (Fix intermittent read hangs on reused HTTP/2 and pooled HTTP/1.1 connections #884).
• HTTP/2: sync reads now have a per-stream recv_timeout watchdog so a lost frame fails fast.
• HTTP/1.1: pooled connections with unsolicited idle data are dropped at checkout instead of having the bytes discarded; keep-alive and Reused socket closing connection #544 detection preserved.