weston: Clip window title text to the frame

Fixes an issue with text overflowing the available frame space.

shared/cairo-util.c

@@ -401,6 +401,11 @@ theme_render_frame(struct theme *t,
 		    width - t->margin * 2, height - t->margin * 2,
 		    t->width, t->titlebar_height);
 
+	cairo_rectangle (cr, t->margin + t->width, t->margin,
+			 width - (t->margin + t->width) * 2,
+			 t->titlebar_height - t->width);
+	cairo_clip(cr);
+
 	cairo_set_operator(cr, CAIRO_OPERATOR_OVER);
 	cairo_select_font_face(cr, "sans",
 			       CAIRO_FONT_SLANT_NORMAL,