Fix spurious assert when creating multiline wxTextCtrl from XRC.

Don't try to set the hint unconditionally, this doesn't work with multiline
text controls and so resulted in an assert when trying to create one from XRC
since the changes of r76629.

Closes #16317.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@76666 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/xrc/xh_text.cpp

@@ -69,7 +69,9 @@ wxObject *wxTextCtrlXmlHandler::DoCreateResource()
     if (HasParam(wxT("maxlength")))
         text->SetMaxLength(GetLong(wxT("maxlength")));
 
-    text->SetHint(GetText(wxS("hint")));
+    const wxString hint = GetText(wxS("hint"));
+    if (!hint.empty())
+        text->SetHint(hint);
 
     return text;
 }