Merge r1893014, r1893073 from trunk:

Merge r1893014, r1893073 from trunk:

mpm_event: Fix children processes possibly not stopped on graceful restart.

The number of children spawned can go above active_daemons_limit due to
exponential idle_spawn_rate growth (x 2), enforce the upper limit in
perform_idle_server_maintenance().  PR 63169.

Submitted by: Joel Self <joelself gmail.com>

mpm_event: Follow up to r1893014: log when children are not spawned.

Log at trace1 level when active_daemons >= active_daemons_limit and we won't
spawn children. Reset free_length to avoid negative value in this case too.

Submitted by: ylavic
Reviewed by: ylavic, covener, rpluem

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.4.x@1893109 13f79535-47bb-0310-9956-ffa450edef68