mpm_event(opt), mpm_worker: follow up to r1635521.
Allocate retained idle_spawn_rate vector on the process pool.

git-svn-id: http://svn.apache.org/repos/asf/httpd/httpd/trunk@1640161 13f79535-47bb-0310-9956-ffa450edef68
mpm_prefork: follow up to r1635521.
Avoid oddity on bucket_make_child_record overflow.

git-svn-id: http://svn.apache.org/repos/asf/httpd/httpd/trunk@1640184 13f79535-47bb-0310-9956-ffa450edef68