meson.build: compile GLib schemas on install

Run a script as a post install to make sure that all GLib schemas are compiled

build-aux/post_install.py

@@ -0,0 +1,14 @@
+#!/usr/bin/python3
+
+import os
+import subprocess
+import sys
+
+destdir = os.environ.get('DESTDIR', '')
+
+if not destdir and len(sys.argv) > 1:
+    datadir = sys.argv[1]
+
+    print('Compiling gsettings schemas...')
+    subprocess.call(['glib-compile-schemas', os.path.join(datadir, 'glib-2.0', 'schemas')])
+