Add wxAuiPaneInfo::IsDockable().

This function checks if the pane can be docked at any side. It is useful in
its own right but most importantly is needed to fix compilation broken in
r66005 which used it before it was added.

See #12648.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@66007 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/aui/framemanager.h

@@ -239,6 +239,11 @@ public:
     bool IsBottomDockable() const { return HasFlag(optionBottomDockable); }
     bool IsLeftDockable() const { return HasFlag(optionLeftDockable); }
     bool IsRightDockable() const { return HasFlag(optionRightDockable); }
+    bool IsDockable() const
+    {
+        return HasFlag(optionTopDockable | optionBottomDockable |
+                        optionLeftDockable | optionRightDockable);
+    }
     bool IsFloatable() const { return HasFlag(optionFloatable); }
     bool IsMovable() const { return HasFlag(optionMovable); }
     bool IsDestroyOnClose() const { return HasFlag(optionDestroyOnClose); }