libgcrypt/cross: Fix build for mingw-w64.

Especially for the 64bit mingw target, because libgcrypt contains
protected mode assembly.

Also, this adds gettext to the crossAttrs of libgpg-error, because it
tries to regenerate the MO files.

Signed-off-by: aszlig <aszlig@redmoonstudios.org>
Use mingw-w64 for 32bit Windows builds as well.

Mingw(32) is rather poorly maintaned and has quite a lot of bugs. And
because our Windows cross builds were also poorly maintained and most of
the cross-tests were broken as well, I'm just taking this step and try
to switch to mingw-w64 for everything "cross Windows".

Signed-off-by: aszlig <aszlig@redmoonstudios.org>
SDL/cross: Drop --disable-directx.

This is no longer needed, because we've already fixed the dynamic
cross-linker.

Signed-off-by: aszlig <aszlig@redmoonstudios.org>