made wx/debug.h C++ header again (reverting changes of r24896); simply don't include it from wx/defs.h when compiling C files which have no need for the stuff defined in it anyhow

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@59702 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/defs.h

@@ -541,9 +541,6 @@ typedef short int WXTYPE;
         wxDEPRECATED(func) { body }
 #endif
 
-/*  everybody gets the assert and other debug macros */
-#include "wx/debug.h"
-
 /*  NULL declaration: it must be defined as 0 for C++ programs (in particular, */
 /*  it must not be defined as "(void *)0" which is standard for C but completely */
 /*  breaks C++ code) */
@@ -552,6 +549,10 @@ typedef short int WXTYPE;
 #endif
 
 #ifdef __cplusplus
+
+// everybody gets the assert and other debug macros
+#include "wx/debug.h"
+
     // delete pointer if it is not NULL and NULL it afterwards
     template <typename T>
     inline void wxDELETE(T*& ptr)