[rygel] tracker: Fix SPARQL syntax error

[Jens Georg <jensgeorg src gnome org>]

commit 26abf9727ffa19e9baafdb66df42e25d0b5092d9
Author: Jens Georg <mail jensge org>
Date:   Thu Jan 11 20:19:21 2018 +0100

    tracker: Fix SPARQL syntax error

 .../tracker/rygel-tracker-metadata-values.vala     |    2 +-
 .../tracker/rygel-tracker-search-container.vala    |    2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/src/plugins/tracker/rygel-tracker-metadata-values.vala 
b/src/plugins/tracker/rygel-tracker-metadata-values.vala
index 99f7eb6..8c0e847 100644
--- a/src/plugins/tracker/rygel-tracker-metadata-values.vala
+++ b/src/plugins/tracker/rygel-tracker-metadata-values.vala
@@ -56,7 +56,7 @@ public abstract class Rygel.Tracker.MetadataValues : MetadataContainer {
         var selected = new ArrayList<string> ();
         selected.add ("DISTINCT " +
                       property_map[this.property] +
-                      " AS x");
+                      " AS ?x");
 
         return new SelectionQuery (selected, triplets, null, "?x");
     }
diff --git a/src/plugins/tracker/rygel-tracker-search-container.vala 
b/src/plugins/tracker/rygel-tracker-search-container.vala
index 13f2cc4..a7ac794 100644
--- a/src/plugins/tracker/rygel-tracker-search-container.vala
+++ b/src/plugins/tracker/rygel-tracker-search-container.vala
@@ -215,7 +215,7 @@ public class Rygel.Tracker.SearchContainer : SimpleContainer {
             query.variables = new ArrayList<string> ();
             query.variables.add ("COUNT(" +
                                  SelectionQuery.ITEM_VARIABLE +
-                                 ") AS x");
+                                 ") AS ?x");
 
             yield query.execute (this.resources);