Fixed code checking for bit flags.

Use "flag & bitmask" instead of "flag && bitmask" (resulted in LLVM compiler warning: "Use of logical '&&' with constant operand").

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@76497 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775