[tracker] (5 commits) Non-fast-forward update to branch wip/carlosg/update-perf

[Carlos Garnacho <carlosg src gnome org>]

The branch 'wip/carlosg/update-perf' was changed in a way that was not a fast-forward update.
NOTE: This may cause problems for people pulling from the branch. For more information,
please see:

 https://wiki.gnome.org/Git/Help/NonFastForward

Commits removed from the branch:

  c010fbc... core: Make it possible to find out statement execution erro
  a7eff3e... core: Avoid finding out resource insertion through GError
  c3b9310... core: Drop caching of scarcely run statements
  74bfea1... core: Avoid query for subclasses of a resource
  1fae8ed... libtracker-sparql: Avoid spurious warnings writing D-Bus en

Commits added to the branch:

  294964d... core: Return a boolean on tracker_db_statement_execute()
  7b2491b... core: Avoid finding out resource insertion through GError
  4bfd070... core: Drop caching of scarcely run statements
  ca2421d... core: Avoid query for subclasses of a resource
  96c5dbb... libtracker-sparql: Avoid spurious warnings writing D-Bus en