query log: support showing condition in each "filter"
query log: support showing condition in each "filter"

It's disabled by default. You need to set
GRN_QUERY_LOG_SHOW_CONDITION=yes environment variable to enable it.

If we confirm that this change doesn't have big impact for performance
and doesn't cause a crash for any query.

cosmo0920/groonga,naoa/groonga,cosmo0920/groonga,naoa/groonga,cosmo0920/groonga,naoa/groonga,groonga/groonga,komainu8/groonga,kenhys/groonga,groonga/groonga,komainu8/groonga,cosmo0920/groonga,groonga/groonga,kenhys/groonga,cosmo0920/groonga,groonga/groonga,kenhys/groonga,cosmo0920/groonga,naoa/groonga,groonga/groonga,naoa/groonga,naoa/groonga,komainu8/groonga,cosmo0920/groonga,komainu8/groonga,kenhys/groonga,kenhys/groonga,kenhys/groonga,komainu8/groonga,naoa/groonga,naoa/groonga,groonga/groonga,kenhys/groonga,groonga/groonga,komainu8/groonga,komainu8/groonga,komainu8/groonga,kenhys/groonga,groonga/groonga,cosmo0920/groonga