Reduce dependencies on TransImageGetter.h
diff --git a/common/rfb/TightEncoder.h b/common/rfb/TightEncoder.h
index 4fff083..465d8ed 100644
--- a/common/rfb/TightEncoder.h
+++ b/common/rfb/TightEncoder.h
@@ -21,7 +21,6 @@
 
 #include <rdr/MemOutStream.h>
 #include <rdr/ZlibOutStream.h>
-#include <rfb/TransImageGetter.h>
 #include <rfb/Encoder.h>
 
 // FIXME: Check if specifying extern "C" is really necessary.
@@ -32,6 +31,8 @@
 
 namespace rfb {
 
+  class TransImageGetter;
+
   struct TIGHT_CONF {
     unsigned int maxRectSize, maxRectWidth;
     unsigned int monoMinRectSize;