X86_mscoff / x86_64 as default for dub projects (windows)

[kinke]

On Friday, 7 December 2018 at 13:58:12 UTC, Dennis wrote:
> My biggest gripe is this confusing matrix of compiler flags:
>
>       default  -m32     -m32mscoff  -m64
> dmd   OMF      OMF      COFF-32     COFF-64
> ldc   COFF-64  COFF-32  Error       COFF-64

Some corrections for LDC:
* The default depends on the host. If you're using a 64-bit LDC 
executable, it defaults to producing 64-bit code.
* `-m32mscoff` is supported by LDMD, which is the DMD-compatible 
wrapper (and simply translates it to `-m32` for the LDC 
executable).