[PATCH] dynamic_cert_mem_cache_size option related fixes

Hi all,

While working on 4005 bug, we found some problems, which fixed with the
attached patch:
1) The dynamic_cert_mem_cache_size does not change on reconfigure
2) When dynamic_cert_mem_cache_size of http_port set to 0 then:
   a) The dynamic certs cache is grow unlimited.
      The attached patch just disables certificates caching
      when this option set to 0.
   b) Huge amount of memory appeared as free cache memory in
      "Cached ssl certificates statistic" page of cache manager.
      This problem caused because of a signed to unsigned int
      conversion.

I must note that this patch changes the current behaviour of
dynamic_cert_mem_cache_size option of http_port:
Currently the size of cache is unlimited when it is set to 0, but this
patch disables the cache when this option set to 0.

Regards,
   Christos