Remove wxPM, wxWidgets port to OS/2.

This port is not used and is not being worked on, so remove it to reduce the
amount of the code which needs to be updated for every global change.

Also remove tests for VisualAge compiler which isn't used since ages.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@76533 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/mdi.h

@@ -350,7 +350,6 @@ public:
     // probably not functional?)
     #if defined(__WXCOCOA__) || \
         defined(__WXMOTIF__) || \
-        defined(__WXPM__) || \
         defined(__WXUNIVERSAL__)
         #define wxUSE_GENERIC_MDI_AS_NATIVE   1
     #else