[ghex] build: Use LINGUAS file for help

[Piotr Drąg <piotrdrag src gnome org>]

commit b95bef1756d8e79091a8e92656a121205f02b2e3
Author: Piotr Drąg <piotrdrag gmail com>
Date:   Sun Mar 18 18:10:30 2018 +0100

    build: Use LINGUAS file for help
    
    The old method is deprecated.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=794450

 help/LINGUAS     |   17 +++++++++++++++++
 help/meson.build |   23 +----------------------
 2 files changed, 18 insertions(+), 22 deletions(-)
---
diff --git a/help/LINGUAS b/help/LINGUAS
new file mode 100644
index 0000000..f940bd0
--- /dev/null
+++ b/help/LINGUAS
@@ -0,0 +1,17 @@
+cs
+de
+el
+es
+fr
+id
+it
+ja
+ko
+oc
+pt_BR
+ru
+sl
+sv
+th
+zh_CN
+zh_TW
diff --git a/help/meson.build b/help/meson.build
index e2c15e7..9c579d4 100644
--- a/help/meson.build
+++ b/help/meson.build
@@ -8,30 +8,9 @@ help_media = [
   'figures/ghex_window_open.png'
 ]
 
-help_languages = [
-  'cs',
-  'de',
-  'el',
-  'es',
-  'fr',
-  'id',
-  'it',
-  'ja',
-  'ko',
-  'oc',
-  'pt_BR',
-  'ru',
-  'sl',
-  'sv',
-  'th',
-  'zh_CN',
-  'zh_TW'
-]
-
 gnome.yelp(
   meson.project_name(),
   sources: help_pages,
   media: help_media,
-  symlink_media: false,
-  languages: help_languages
+  symlink_media: false
 )