Add system variable to show whether libgroonga supports zlib/lz4 or not

I've implemented the following.
  * Add system variable to show whether libgroonga supports zlib/lz4 or not.
  * Skip the current tests when libgroonga doesn't support zlib/lz4.
  * Add tests for libgroonga doesn't support zlib/lz4 cases. In the
    cases, Mroonga should reports a warning.