Remove MicroWindows support.

MicroWindows (aka Nano-X) support hasn’t been updated since 2010 and last work for it in wxWidgets happened more than 10 years ago.

src/common/intl.cpp

@@ -792,7 +792,7 @@ wxString wxLocale::GetSystemEncodingName()
 {
     wxString encname;
 
-#if defined(__WIN32__) && !defined(__WXMICROWIN__)
+#if defined(__WIN32__)
     // FIXME: what is the error return value for GetACP()?
     UINT codepage = ::GetACP();
     encname.Printf(wxS("windows-%u"), codepage);
@@ -849,7 +849,7 @@ wxString wxLocale::GetSystemEncodingName()
 /* static */
 wxFontEncoding wxLocale::GetSystemEncoding()
 {
-#if defined(__WIN32__) && !defined(__WXMICROWIN__)
+#if defined(__WIN32__)
     UINT codepage = ::GetACP();
 
     // wxWidgets only knows about CP1250-1257, 874, 932, 936, 949, 950