[tracker-miners/sam/build-fix] build: Fix error in -Dtracker_core=system case

[Sam Thursfield <sthursfield src gnome org>]

commit 8d31153697af2ceacab9b44177ebbcc564711589
Author: Sam Thursfield <sam afuera me uk>
Date:   Sat Apr 4 23:10:23 2020 +0200

    build: Fix error in -Dtracker_core=system case
    
    This was a regression I introduced in 4ca42bdd89c488522bf234deef60151cbffaaa0b

 meson.build | 2 ++
 1 file changed, 2 insertions(+)
---
diff --git a/meson.build b/meson.build
index 8b482a217..1b20c025a 100644
--- a/meson.build
+++ b/meson.build
@@ -32,6 +32,8 @@ if get_option('tracker_core') == 'system'
   tracker_uninstalled_stop_words_dir = join_paths(tracker_sparql.get_pkgconfig_variable('datadir'), 
'tracker', 'stop-words')
   tracker_uninstalled_testutils_dir = tracker_testutils.get_pkgconfig_variable('python_path')
   tracker_uninstalled_nepomuk_ontologies_dir = 
join_paths(tracker_sparql.get_pkgconfig_variable('ontologies_dir'), 'nepomuk')
+
+  tracker_sparql_uninstalled_dir = tracker_sparql.get_pkgconfig_variable('libdir')
 else
   tracker_subproject = subproject('tracker')