This threes example is for the MinGW64 compiler (a Windows
implementation of the GNU C/C++ compiler targeting x86_64, i.e.
64-bit Windows).

Note:
- The Ox development header files must be found during
  compilation. If necessary, modify Makefile.
- Compilation will do nothing, because the DLL is already
  up to date. Delete threes.o and threes.dll to check
  compilation.
- If compilation is successful, threes_64.dll will be created.
- oxl threes.ox to check the compiled DLL (this must be the 64-bit oxl).
- ox/dev/lib64/liboxwin.a is the import library for the Ox DLL,
  created with:
		dlltool -d oxwin_vc.def --dllname oxwin.dll --output-lib lib64\liboxwin.a --export-all
  NB1: in 64-bit code stdcall functions names are exported without decoration
       (i.e. no _ prefix and no @nn suffix).
  NB2: jdsystem.h defines __stdcall (used for JDCALL and OXCALL) and
       __cdecl.
  