Be more aggressive in finding solid rectangles

The previous FIXME was incorrect. The old code did in fact continue
looking over the entire area. This commit restores that old behaviour.
diff --git a/common/rfb/EncodeManager.h b/common/rfb/EncodeManager.h
index a694e06..a3df8f7 100644
--- a/common/rfb/EncodeManager.h
+++ b/common/rfb/EncodeManager.h
@@ -59,6 +59,7 @@
 
     void writeCopyRects(const UpdateInfo& ui);
     void writeSolidRects(Region *changed, const PixelBuffer* pb);
+    void findSolidRect(const Rect& rect, Region *changed, const PixelBuffer* pb);
     void writeRects(const Region& changed, const PixelBuffer* pb);
 
     void writeSubRect(const Rect& rect, const PixelBuffer *pb);