Check for _NL_TIME_FIRST_WEEKDAY declaration

Author: Cameron Nemo

core/Model/CalendarModel.vala

@@ -68,7 +68,11 @@ public class Maya.Model.CalendarModel : Object {
     }
 
     private CalendarModel () {
+#if HAVE_NL_TIME_FIRST_WEEKDAY
         int week_start = Posix.NLTime.FIRST_WEEKDAY.to_string ().data[0];
+#else
+        int week_start = 0;
+#endif
         if (week_start >= 1 && week_start <= 7) {
             week_starts_on = (Maya.Settings.Weekday)week_start-1;
         }

meson.build

@@ -31,13 +31,18 @@ folks_dep = dependency('folks')
 geocode_glib_dep = dependency('geocode-glib-1.0')
 gclue_dep = dependency('libgeoclue-2.0')
 
-m_dep = meson.get_compiler('c').find_library('m', required : false)
+cc = meson.get_compiler('c')
+m_dep = cc.find_library('m', required : false)
 libnotify_dep = dependency('libnotify', required: false)
 
 if libnotify_dep.found()
     add_project_arguments('--define=HAVE_LIBNOTIFY', language: 'vala')
 endif
 
+if cc.has_header_symbol('langinfo.h', '_NL_TIME_FIRST_WEEKDAY')
+    add_project_arguments('--define=HAVE_NL_TIME_FIRST_WEEKDAY', language: 'vala')
+endif
+
 gresource_calendar = gnome.compile_resources(
     'gresource_calendar',
     'data/maya.gresource.xml',