Extract operator<<(ostream, wxFileName) from filename test.

Putting this function in a header allows to reuse it in other tests, e.g. the
upcoming wxFileSystemWatcher one.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@62473 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

tests/filename/filenametest.cpp

@@ -28,15 +28,7 @@
     #include "wx/msw/registry.h"
 #endif // __WXMSW__
 
-// ----------------------------------------------------------------------------
-// local functions
-// ----------------------------------------------------------------------------
-
-// define stream inserter for wxFileName to use it in CPPUNIT_ASSERT_EQUAL()
-inline std::ostream& operator<<(std::ostream& o, const wxFileName& fn)
-{
-    return o << fn.GetFullPath();
-}
+#include "testfile.h"
 
 // ----------------------------------------------------------------------------
 // test data