No real changes, just use const_cast<> instead of C casts.

No real changes, just use const_cast<> instead of C casts.

Replace many comments indicating that the C cast used was really a
const_cast<> with the proper cast itself. There is no reason to not use it any
longer, all the supported compilers understand it.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@65861 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775