Threads: fixed request hang with aio_write and subrequests. If the subrequest is already finalized, the handler set with aio_write may still be used by sendfile in threads when using range requests (see also e4c1f5b32868, and the original note in 9fd738b85fad). Calling already finalized subrequest's r->write_event_handler in practice results in request hang in some cases. Fix is to trigger connection event handler if the subrequest was already finalized.

# Copyright (C) Igor Sysoev
# Copyright (C) Nginx, Inc.


ngx_include="unistd.h";      . auto/include
ngx_include="inttypes.h";    . auto/include
ngx_include="limits.h";      . auto/include
ngx_include="sys/filio.h";   . auto/include
ngx_include="sys/param.h";   . auto/include
ngx_include="sys/mount.h";   . auto/include
ngx_include="sys/statvfs.h"; . auto/include
ngx_include="crypt.h";       . auto/include