build: Move timezone languages to LINGUAS file

The timezone panel uses translations for the existing timezone
names. This was using a set of predefined languages inside the
meson's build file.

This set of languages has been moved to the LINGUAS file.

https://bugzilla.gnome.org/show_bug.cgi?id=787588

panels/datetime/po-timezones/LINGUAS

@@ -0,0 +1,69 @@
+am
+ar
+as
+ast
+bg
+bn
+bn_IN
+bs
+ca
+cs
+cy
+da
+de
+el
+en_GB
+es
+et
+fa
+fi
+fr
+gl
+gu
+he
+hi
+hr
+hu
+id
+ilo
+is
+it
+ja
+ka
+kn
+ko
+ku
+lo
+lt
+lv
+mai
+mk
+ml
+mr
+ms
+nb
+nds
+nl
+nn
+or
+pa
+pl
+pt
+pt_BR
+ro
+ru
+si
+sk
+sl
+sq
+sr
+sr@latin
+sv
+ta
+te
+tr
+uk
+ur
+vi
+zh_CN
+zh_TW

panels/datetime/po-timezones/meson.build

@@ -1,73 +1 @@
-linguas = [
-  'am',
-  'ar',
-  'as',
-  'ast',
-  'bg',
-  'bn',
-  'bn_IN',
-  'bs',
-  'ca',
-  'cs',
-  'cy',
-  'da',
-  'de',
-  'el',
-  'en_GB',
-  'es',
-  'et',
-  'fa',
-  'fi',
-  'fr',
-  'gl',
-  'gu',
-  'he',
-  'hi',
-  'hr',
-  'hu',
-  'id',
-  'ilo',
-  'is',
-  'it',
-  'ja',
-  'ka',
-  'kn',
-  'ko',
-  'ku',
-  'lo',
-  'lt',
-  'lv',
-  'mai',
-  'mk',
-  'ml',
-  'mr',
-  'ms',
-  'nb',
-  'nds',
-  'nl',
-  'nn',
-  'or',
-  'pa',
-  'pl',
-  'pt',
-  'pt_BR',
-  'ro',
-  'ru',
-  'si',
-  'sk',
-  'sl',
-  'sq',
-  'sr',
-  'sr@latin',
-  'sv',
-  'ta',
-  'te',
-  'tr',
-  'uk',
-  'ur',
-  'vi',
-  'zh_CN',
-  'zh_TW'
-]
-
-i18n.gettext(control_center_gettext + '-timezones', languages: linguas, preset: 'glib')
+i18n.gettext(control_center_gettext + '-timezones', preset: 'glib')