Win64 MinGW

[Daniel Green]

MinGW-w64 D1 with phobos has been successfully compiled.  Phobos 
contained 3 errors.  Two were Windows function calls.  Phobos uses 
size_t but Win64 uses uint.  The other was with the GC relating to 
Windows stack information.  Several functions in the GC expect uint 
which causes warnings and should probably be made size_t.

MinGW-w64 D2 with phobos has been successfully compiled.  This one was a 
little more work.

In both cases GDC compiled without issues.  The majority of the D2 
issues are <symbol>.length defaulting to size_t and being used as a 
function parameter wanting int/uint.  Most Windows API calls that do not 
deal with memory have the same signature as Win32.

There are still a few quirks I don't understand about the build process 
until I get those figured out I won't release any binaries.