* [wxwidgets] move setup.h to include
Also remove lib/mswu and debug/lib/mswud. They only contain setup.h.
Fixes#3180.
Closes#4251.
* [wxwidgets] remove include/msvc directory
The only thing in include/msvc is include/msvc/wx/setup.h which is a
"wrapper" around the real setup.h. The wrapper setup.h is hard-coded to
include the real setup.h from lib but since the real setup.h is now in
include/wx the wrapper has become useless.
* [wxwidgets] Fix osx build. Slight modernization.
