Avoid unnecessary compilation dependency on DoxygenTranslator.h.

Use forward declaration instead of including this header in the common header
used by all languages (and not just the two of them that actually use
DoxygenTranslator currently).

Source/Modules/swigmod.h

@@ -17,7 +17,6 @@
 #include "swig.h"
 #include "preprocessor.h"
 #include "swigwarn.h"
-#include "../DoxygenTranslator/src/DoxygenTranslator.h"
 
 #if !defined(HAVE_BOOL)
 typedef int bool;
@@ -345,8 +344,9 @@ protected:
   /* Director language module */
   int director_language;
 
-  // Class instance to translate comments
-  DoxygenTranslator *doxygenTranslator;
+  /* Used to translate Doxygen comments to target documentation format */
+  class DoxygenTranslator *doxygenTranslator;
+
 private:
   Hash *symtabs; /* symbol tables */
   Hash *classtypes;