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

configure

@@ -39218,7 +39218,7 @@ if test "${wx_cv_func_vsnprintf_decl+set}" = set; then
   echo $ECHO_N "(cached) $ECHO_C" >&6
 else
 
-                                                            cat >conftest.$ac_ext <<_ACEOF
+                                    cat >conftest.$ac_ext <<_ACEOF
 /* confdefs.h.  */
 _ACEOF
 cat confdefs.h >>conftest.$ac_ext
@@ -39227,12 +39227,6 @@ cat >>conftest.$ac_ext <<_ACEOF
 
                     #include <stdio.h>
                     #include <stdarg.h>
-                    #ifdef __MSL__
-                    #if __MSL__ >= 0x6000
-                    namespace std {}
-                    using namespace std;
-                    #endif
-                    #endif
 
 int
 main ()