Remove support for MetroWerks CodeWarrior compiler.

This compiler doesn't exist any more and was probably unsupported even in 2.8,
let alone 2.9, so remove all the __MWERKS__ tests to simplify things.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@71102 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/msw/utilsexc.cpp

@@ -48,10 +48,8 @@
 
 #if !defined(__GNUWIN32__) && !defined(__WXMICROWIN__) && !defined(__WXWINCE__)
     #include <direct.h>
-#ifndef __MWERKS__
     #include <dos.h>
 #endif
-#endif
 
 #if defined(__GNUWIN32__)
     #include <sys/unistd.h>