set doxygen variable ensuring macro definitions of type MY_FOO(arg) dont mess up doc generation

Documentation/Doxyfile.txt.in

@@ -1608,7 +1608,10 @@ EXPAND_AS_DEFINED      =
 # that are alone on a line, have an all uppercase name, and do not end with a
 # semicolon, because these will confuse the parser if not removed.
 
-SKIP_FUNCTION_MACROS   = NO
+# CTK Note: Changed this back to the default YES,
+# in order to avoid trouble using f.ex. Q_DECLARE_PRIVATE(classname),
+# which hides later method declarations.
+SKIP_FUNCTION_MACROS   = YES
 
 #---------------------------------------------------------------------------
 # Configuration::additions related to external references