never ending loop in utils.c (overrun cmd buffer)

In the file "utils.c":
1. a while loop is started
     => OK
2. within this loop a check is done if there are no item's so,
   this loop will sleep a little bit.
     => OK
3. checking if there are less items buffered, than configured
     => But what if these values are equal??

300.000 > 250.000 => all BufferSlot used => Nagios is going crazy.

Solution:
The command_file_worker_thread has to wait until event.c is
catching up some commands from the buffer

IssueID: #87