applied (part of) Alexey Leko's patch

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@8819 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/common/log.cpp

@@ -50,6 +50,8 @@
 #include  "wx/log.h"
 #include  "wx/thread.h"
 
+#if wxUSE_LOG
+
 // other standard headers
 #include  <errno.h>
 #include  <stdlib.h>
@@ -790,3 +792,4 @@ void wxOnAssert(const wxChar *szFile, int nLine, const wxChar *szMsg)
 
 #endif  //WXDEBUG
 
+#endif //wxUSE_LOG