Improvements for building minimal builds and new ports: wxUSE_* usage and minor cleaning.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@39633 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/defs.h

@@ -597,6 +597,13 @@ typedef int wxWindowID;
     #define WXUNUSED_IN_WINCE(param)  param
 #endif
 
+/*  unused parameters in non stream builds */
+#if wxUSE_STREAMS
+    #define WXUNUSED_UNLESS_STREAMS(param)  param
+#else
+    #define WXUNUSED_UNLESS_STREAMS(param)  WXUNUSED(param)
+#endif
+
 /*  some compilers give warning about a possibly unused variable if it is */
 /*  initialized in both branches of if/else and shut up if it is initialized */
 /*  when declared, but other compilers then give warnings about unused variable */