Fix getting wxEVT_TEXT_ENTER from wxSearchCtrl

wxSearchCtrl never generated this event, at least under MSW, even though
the code to forward it from wxSearchTextCtrl was present in it, because
it was never generated in the first place without wxTE_PROCESS_ENTER.

Fix this by simply always using this style in wxSearchTextCtrl.

src/generic/srchctlg.cpp

@@ -49,7 +49,7 @@ class wxSearchTextCtrl : public wxTextCtrl
 public:
     wxSearchTextCtrl(wxSearchCtrl *search, const wxString& value, int style)
         : wxTextCtrl(search, wxID_ANY, value, wxDefaultPosition, wxDefaultSize,
-                     (style & ~wxBORDER_MASK) | wxNO_BORDER)
+                     (style & ~wxBORDER_MASK) | wxNO_BORDER | wxTE_PROCESS_ENTER)
     {
         m_search = search;