build: Check translations using a script

Use a bash script to check the translations as we used to do during
the autotools-based distcheck.

po/check-translations.sh

@@ -0,0 +1,14 @@
+#!/bin/bash
+
+po_dir=$(dirname $0)
+
+for i in $po_dir/*.po ; do
+    if ! grep -q `basename $i | sed 's,.po,,'` $po_dir/LINGUAS; then
+        echo '**********************************';
+        echo '***' `basename $i | sed 's,.po,,'` missing from po/LINGUAS '***' ;
+        echo '**********************************';
+        exit 1;
+    fi;
+done;
+
+exit 0

po/meson.build

@@ -1 +1,6 @@
 i18n.gettext(meson.project_name(), preset: 'glib')
+
+test('check-translations',
+    find_program('check-translations.sh'),
+    suite: ['dist'],
+)