[polari] build: Update appdata install path

[Gitlab Administrative User <gitlab src gnome org>]

commit 918103168e8154b1764e75b14ba1e95953838372
Author: Florian Müllner <fmuellner gnome org>
Date:   Wed Nov 8 19:30:54 2017 +0100

    build: Update appdata install path
    
    The appstream spec was updated a while ago, so install our appdata
    to the new location[0] instead of the legacy path.
    
    [0] https://www.freedesktop.org/software/appstream/docs/chap-Metadata.html#spec-component-location

 data/appdata/meson.build | 2 +-
 meson.build              | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/data/appdata/meson.build b/data/appdata/meson.build
index a01a4a4..f65cbc1 100644
--- a/data/appdata/meson.build
+++ b/data/appdata/meson.build
@@ -4,7 +4,7 @@ i18n.merge_file(appdata,
   output: appdata,
   po_dir: '../../po',
   install: true,
-  install_dir: appdatadir
+  install_dir: metainfodir
 )
 
 if (appstream_util.found())
diff --git a/meson.build b/meson.build
index 048643b..e66afd6 100644
--- a/meson.build
+++ b/meson.build
@@ -18,9 +18,9 @@ datadir = get_option('datadir')
 pkglibdir = join_paths(libdir, meson.project_name())
 pkgdatadir = join_paths(datadir, meson.project_name())
 
-appdatadir = join_paths(datadir, 'appdata')
 desktopdir = join_paths(datadir, 'applications')
 icondir = join_paths(datadir, 'icons')
+metainfodir = join_paths(datadir, 'metainfo')
 schemadir = join_paths(datadir, 'glib-2.0', 'schemas')
 servicedir = join_paths(datadir, 'dbus-1', 'services')
 tpclientdir = join_paths(datadir, 'telepathy', 'clients')