Merge r1818804, r1818951, r1818958, r1818960, r1819027, r1819214, r1820035 from trunk:

Merge r1818804, r1818951, r1818958, r1818960, r1819027, r1819214, r1820035 from trunk:

mpm_event: close connections not reported as handled by any module.

This avoids losing track of them and leaking scoreboard entries.
PR 61551.

mpm_event: follow up to r1818804.

Address corner case where connection is aborted due to ap_run_pre_connection()
failure, and update comment about ap_run_process_connection() expected return
status and state.

mpm_event: follow up to r1818804 and r1818951.

Align comment and fix typos.

mpm_event: follow up to r1818804.

Allow DONE as a successful ap_run_process_connection() return value, for
instance h2_conn_run() and h2_task_process_conn() uses it, third-party
modules may too...

mpm_event: follow up to r1818804 and r1818951.

Be more correct in comment about CONN_STATE_WRITE_COMPLETION.
We currently have/need no state to simply wait for readability on a socket,
so the previous comment was misleading. Write completion can't be used for
a simple "wait for read event and come back to process_connection hooks".

mpm_event: follow up to r1818804 and r1818960.

Align mod_http2 with expected returned state from process_connection hooks in
async MPMs.
When the master connection is handled, enter CONN_STATE_LINGER in any case.

Add missing APLOGNO

Submitted by: ylavic, jailletc36
Reviewed by: ylavic, icing, covener

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.4.x@1820796 13f79535-47bb-0310-9956-ffa450edef68