Clear wxFontEnumerator face names cache on library shutdown

Don't rely on it being done during statics cleanup as this doesn't work
if the library is shutdown and re-initialized.

Use a module to do the cleanup, just as it's already done for a lot of
other global data in wx.

src/common/fontenumcmn.cpp

@@ -26,6 +26,31 @@
 #if wxUSE_FONTENUM
 
 #include "wx/fontenum.h"
+#include "wx/module.h"
+
+namespace
+{
+
+// Cached result of GetFacenames().
+wxArrayString gs_allFacenames;
+
+// Module used to ensure the cache is cleared on library shutdown and so is not
+// reused if it re-initialized again later.
+class wxFontEnumCacheCleanupModule : public wxModule
+{
+public:
+    wxFontEnumCacheCleanupModule() { }
+
+    bool OnInit() wxOVERRIDE { return true; }
+    void OnExit() wxOVERRIDE { gs_allFacenames.clear(); }
+
+private:
+    wxDECLARE_DYNAMIC_CLASS(wxFontEnumCacheCleanupModule);
+};
+
+wxIMPLEMENT_DYNAMIC_CLASS(wxFontEnumCacheCleanupModule, wxModule);
+
+} // anonymous namespace
 
 // ============================================================================
 // implementation
@@ -79,7 +104,8 @@ bool wxFontEnumerator::IsValidFacename(const wxString &facename)
 {
     // we cache the result of wxFontEnumerator::GetFacenames supposing that
     // the array of face names won't change in the session of this program
-    static wxArrayString s_arr = wxFontEnumerator::GetFacenames();
+    if ( gs_allFacenames.empty() )
+        gs_allFacenames = wxFontEnumerator::GetFacenames();
 
 #ifdef __WXMSW__
     // Quoting the MSDN:
@@ -95,7 +121,7 @@ bool wxFontEnumerator::IsValidFacename(const wxString &facename)
 #endif
 
     // is given font face name a valid one ?
-    if (s_arr.Index(facename, false) == wxNOT_FOUND)
+    if (gs_allFacenames.Index(facename, false) == wxNOT_FOUND)
         return false;
 
     return true;