mpm_winnt: Drop the APLOG_DEBUG diagnostic saying how many thread

mpm_winnt: Drop the APLOG_DEBUG diagnostic saying how many thread
are blocked on the I/O completion port during the shutdown.

Prior to r1801635, the shutdown code required to know the amount of blocked
threads, as it has been dispatching the same amount of completion packets.
But this no longer holds, and the only reason why we maintain the
corresponding g_blocked_threads variable is because of this debug
diagnostic message.

Drop it in order to reduce complexity of the quite critical code in the
winnt_get_connection() function and to reduce the amount of global
variables.

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1801640 13f79535-47bb-0310-9956-ffa450edef68