Reconcile HAVE_VARIADIC_MACROS and wxHAS_VARIADIC_MACROS definitions.

The main user-visible effect of this change is that giving configure
--disable-vararg-macros argument now really disables the use of variadic
macros whereas it didn't disable them in wx/cpp.h before.

It is, of course, also less confusing to not have two very similar but
different symbols.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@74489 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/defs.h

@@ -425,17 +425,6 @@ typedef short int WXTYPE;
     #endif /* va_copy/!va_copy */
 #endif /* wxVaCopy */
 
-#ifndef HAVE_VARIADIC_MACROS
-    #if wxCHECK_WATCOM_VERSION(1,2)
-        #define HAVE_VARIADIC_MACROS
-    #endif
-
-    #if wxCHECK_VISUALC_VERSION(9)
-        #define HAVE_VARIADIC_MACROS
-    #endif
-#endif /* HAVE_VARIADIC_MACROS */
-
-
 #ifndef HAVE_WOSTREAM
     /*
         Mingw <= 3.4 and all versions of Cygwin don't have std::wostream