Move __MINGW64_TOOLCHAIN__ definition to wx/msw/gccpriv.h.

__MINGW64_VERSION_MAJOR is defined only in _mingw.h, so it was never defined
in wx/compiler.h, included before any other headers and we can't include
_mingw.h for the same reason we must define wxCHECK_MINGW32_VERSION() in
wx/msw/gccpriv.h: this has to be done after defining UNICODE/_UNICODE, but
wx/compiler.h is included before this.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@77532 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/compiler.h

@@ -106,36 +106,8 @@
 #endif
 
 /*
-   This macro can be used to check that the version of mingw32 CRT is at least
-   maj.min
+    wxCHECK_MINGW32_VERSION() is defined in wx/msw/gccpriv.h which is included
+    later, see comments there.
  */
 
-/*
-    Define Mingw identification symbols, wxCHECK_MINGW32_VERSION() is defined in
-    wx/msw/gccpriv.h which is included later, see comments there.
- */
-#ifdef __MINGW32__
-/*
-    MinGW-w64 project provides compilers for both Win32 and Win64 but only
-    defines the same __MINGW32__ symbol for the former as MinGW32 toolchain
-    which is quite different (notably doesn't provide many SDK headers that
-    MinGW-w64 does include). So we define a separate symbol which, unlike the
-    predefined __MINGW64__, can be used to detect this toolchain in both 32 and
-    64 bit builds.
-
-    And define __MINGW32_TOOLCHAIN__ for consistency and also because it's
-    convenient as we often want to have some workarounds only for the (old)
-    MinGW32 but not (newer) MinGW-w64, which still predefines __MINGW32__.
- */
-#   ifdef __MINGW64_VERSION_MAJOR
-#       ifndef __MINGW64_TOOLCHAIN__
-#           define __MINGW64_TOOLCHAIN__
-#       endif
-#   else
-#       ifndef __MINGW32_TOOLCHAIN__
-#           define __MINGW32_TOOLCHAIN__
-#       endif
-#   endif
-#endif
-
 #endif // _WX_COMPILER_H_