{time,clock}overlay: Hold the class-global pango mutex when changing the pango context

ext/pango/gstclockoverlay.c

@@ -163,6 +163,7 @@ gst_clock_overlay_class_init (GstClockOverlayClass * klass)
           "Format to use for time and date value, as in strftime.",
           DEFAULT_PROP_TIMEFORMAT, G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS));
 
+  g_mutex_lock (GST_TEXT_OVERLAY_CLASS (klass)->pango_lock);
   context = GST_TEXT_OVERLAY_CLASS (klass)->pango_context;
 
   pango_context_set_language (context, pango_language_from_string ("en_US"));
@@ -177,6 +178,7 @@ gst_clock_overlay_class_init (GstClockOverlayClass * klass)
   pango_font_description_set_size (font_description, 18 * PANGO_SCALE);
   pango_context_set_font_description (context, font_description);
   pango_font_description_free (font_description);
+  g_mutex_unlock (GST_TEXT_OVERLAY_CLASS (klass)->pango_lock);
 }
 
 

ext/pango/gsttimeoverlay.c

@@ -123,6 +123,7 @@ gst_time_overlay_class_init (GstTimeOverlayClass * klass)
 
   gsttextoverlay_class->get_text = gst_time_overlay_get_text;
 
+  g_mutex_lock (GST_TEXT_OVERLAY_CLASS (klass)->pango_lock);
   context = GST_TEXT_OVERLAY_CLASS (klass)->pango_context;
 
   pango_context_set_language (context, pango_language_from_string ("en_US"));
@@ -137,6 +138,7 @@ gst_time_overlay_class_init (GstTimeOverlayClass * klass)
   pango_font_description_set_size (font_description, 18 * PANGO_SCALE);
   pango_context_set_font_description (context, font_description);
   pango_font_description_free (font_description);
+  g_mutex_unlock (GST_TEXT_OVERLAY_CLASS (klass)->pango_lock);
 }
 
 static void