Remove unused PangoContext variable from X11 code

It's has been there since basically always, but seems to never have been
used, so remove it to avoid warnings.

src/x11/pango_x.cpp

@@ -96,12 +96,9 @@ x11_draw_layout_line_with_colors( Drawable         drawable,
     PangoRectangle overall_rect;
     PangoRectangle logical_rect;
     PangoRectangle ink_rect;
-    PangoContext *context;
     gint x_off = 0;
     gint rise = 0;
 
-    context = pango_layout_get_context (line->layout);
-
     pango_layout_line_get_extents (line,NULL, &overall_rect);
 
     GSList *tmp_list = line->runs;