Avoid GTK warning "invalid cast from 'GtkTextView' to 'GtkEntry'" when using SetHint()

closes #16321

src/gtk/textctrl.cpp

@@ -851,7 +851,10 @@ GtkEditable *wxTextCtrl::GetEditable() const
 
 GtkEntry *wxTextCtrl::GetEntry() const
 {
-    return GTK_ENTRY(m_text);
+    if (GTK_IS_ENTRY(m_text))
+        return (GtkEntry*)m_text;
+
+    return NULL;
 }
 
 int wxTextCtrl::GTKIMFilterKeypress(GdkEventKey* event) const

src/gtk/textentry.cpp

@@ -521,7 +521,7 @@ bool wxTextEntry::SetHint(const wxString& hint)
 {
 #if GTK_CHECK_VERSION(3,2,0)
     GtkEntry *entry = GetEntry();
-    if (entry && GTK_IS_ENTRY(entry) && gtk_check_version(3,2,0) == NULL)
+    if (entry && gtk_check_version(3,2,0) == NULL)
     {
         gtk_entry_set_placeholder_text(entry, wxGTK_CONV(hint));
         return true;