[gtranslator] Fix plural-forms install and loading

[Daniel Garcia Moreno <danigm src gnome org>]

commit 69bc9ede6547be87e615683dadcf31581a81fff9
Author: Daniel García Moreno <danigm wadobo com>
Date:   Fri Sep 14 12:21:19 2018 +0200

    Fix plural-forms install and loading
    
    See #16

 data/gtr-toolbar.xml | 37 -------------------------------------
 data/layout.xml      | 25 -------------------------
 data/meson.build     |  2 ++
 3 files changed, 2 insertions(+), 62 deletions(-)
---
diff --git a/data/meson.build b/data/meson.build
index fb78835c..51572df2 100644
--- a/data/meson.build
+++ b/data/meson.build
@@ -49,3 +49,5 @@ compiled_schemas = custom_target(
   command: [find_program('glib-compile-schemas'), meson.current_build_dir()]
 )
 
+install_data ('gtr-plural-forms.ini', install_dir: join_paths (gtranslator_pkgdatadir, 'ui'))
+