Put storage class outside WXDLLIMPEXP_DATA_CORE() macros.

The storage class must come first in a declaration so put it in front of
WXDLLIMPEXP_DATA_CORE() and not inside it to avoid warnings from some
compilers (notably Intel one).

Closes #12932.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@66994 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/motif/accel.h

@@ -34,7 +34,7 @@ public:
     wxAcceleratorEntry* GetEntries() const;
 };
 
-WXDLLIMPEXP_DATA_CORE(extern wxAcceleratorTable) wxNullAcceleratorTable;
+extern WXDLLIMPEXP_DATA_CORE(wxAcceleratorTable) wxNullAcceleratorTable;
 
 #endif
 // _WX_ACCEL_H_