Make the code more clear in aui sample and avoid g++ 4 warning.

Make the code more clear in aui sample and avoid g++ 4 warning.

The code used bitwise XOR which was rather difficult to read and also resulted
in g++ 4 warnings about suggested parentheses.

Fix both issues by using bitwise AND and OR in two separate statements instead.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@63633 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775