Windows x64 C-Runtime

[Benjamin Thaut]

Currently DMD will always link against the release version of the 
microsoft C-runtime (libcmt.lib). And as far as I can tell it 
also links against the static version of the c-runtime. We should 
at least support linking against the debug version of the 
c-runtime (libcmtd.lib), maybe with a compiler switch.

There is also a shared version of the microsoft c-runtime but I 
think that one requires a manifest to work correctly (AFAIK). It 
would be nice to have that one too, because it would be the first 
step to allow shared D-dlls.

Kind Regards
Benjamin Thaut