common: Add flatpak_get_tzdir() helper

common/flatpak-utils-base-private.h

@@ -29,7 +29,9 @@
 # define G_DBUS_METHOD_INVOCATION_UNHANDLED FALSE
 #endif
 
-char *flatpak_get_timezone (void);
+const char * flatpak_get_tzdir (void);
+
+char * flatpak_get_timezone (void);
 
 char * flatpak_readlink (const char *path,
                          GError    **error);

common/flatpak-utils-base.c

@@ -28,6 +28,18 @@
 #include <gio/gio.h>
 #include "libglnx.h"
 
+const char *
+flatpak_get_tzdir (void)
+{
+  const gchar *tzdir;
+
+  tzdir = getenv ("TZDIR");
+  if (tzdir)
+    return tzdir;
+
+  return "/usr/share/zoneinfo";
+}
+
 char *
 flatpak_get_timezone (void)
 {