[grilo-plugins/sam/fix-no-chromaprint-crash] tracker: Fix crash if chromaprint plugin isn't installed

[Sam Thursfield <sthursfield src gnome org>]

commit 46d7c0edfbf97ca15c08e5cd1c6d563363843e82
Author: Sam Thursfield <sam afuera me uk>
Date:   Sun Sep 29 16:42:29 2019 +0200

    tracker: Fix crash if chromaprint plugin isn't installed
    
    This is a regression from 7fa5126eace8d9931643f.
    
    See: https://gitlab.gnome.org/GNOME/grilo-plugins/issues/61

 src/tracker/grl-tracker-utils.c | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)
---
diff --git a/src/tracker/grl-tracker-utils.c b/src/tracker/grl-tracker-utils.c
index 86f0f0c8..406f4efc 100644
--- a/src/tracker/grl-tracker-utils.c
+++ b/src/tracker/grl-tracker-utils.c
@@ -325,11 +325,13 @@ grl_tracker_setup_key_mappings (void)
                      "(SELECT tracker:referenceIdentifier(?rg) AS ?rg_id { ?urn nmm:musicAlbum ?album . 
?album tracker:hasExternalReference ?rg . ?rg tracker:referenceSource 
\"https://musicbrainz.org/doc/Release_Group\"; })",
                      "audio");
 
-  insert_key_mapping_with_setter (grl_metadata_key_chromaprint,
-                                  NULL,
-                                  "(select nfo:hashValue(?h) { ?urn nfo:hasHash ?h . ?h nfo:hashAlgorithm 
\"chromaprint\" })",
-                                  "audio",
-                                  set_string_metadata_keys);
+  if (grl_metadata_key_chromaprint != 0) {
+    insert_key_mapping_with_setter (grl_metadata_key_chromaprint,
+                                    NULL,
+                                    "(select nfo:hashValue(?h) { ?urn nfo:hasHash ?h . ?h nfo:hashAlgorithm 
\"chromaprint\" })",
+                                    "audio",
+                                    set_string_metadata_keys);
+  };
 
   insert_key_mapping (GRL_METADATA_KEY_FRAMERATE,
                       "nfo:frameRate",