[tracker] (14 commits) Non-fast-forward update to branch wip/jfelder/external-reference

[Jean Felder <jfelder src gnome org>]

The branch 'wip/jfelder/external-reference' 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:

  ea6a592... 90-tracker.ontology: Add support for ExternalReference
  9e2f0a9... Revert "38-nmm.ontology: Store Musicbrainz IDs for music re

Commits added to the branch:

  24885a7... build: Correctly hide static libtracker-sparql-intermediate (*)
  24287b8... ci: Enable link-time optimization (*)
  444ac9b... build: Make libtracker-common a static library, for real th (*)
  38dc100... Merge branch 'sam/lto-fix' into 'master' (*)
  902ed7a... Merge branch 'sam/static-libtracker-common' into 'master' (*)
  3806940... Updated Spanish translation (*)
  c2bcf89... libtracker-common: Make TrackerDomainOntology totally not a (*)
  18c06d6... Merge branch 'wip/carlosg/domain-ontology-non-object' into  (*)
  6c537a1... functional-tests: Remove 12-transactions test (*)
  a4571aa... tests: Mark file-notifier-test as needing a higher timeout (*)
  b768eb4... Merge branch 'sam/slow-tests' into 'master' (*)
  5e92a38... Update NEWS for 2.3.0 (*)
  1d54e89... 90-tracker.ontology: Add support for ExternalReference
  d217f64... Revert "38-nmm.ontology: Store Musicbrainz IDs for music re

(*) This commit already existed in another branch; no separate mail sent