[Janitorial] Remove CopyMetaFileW->A call

[Vincent Béron]

Indentation in CopyMetaFileW is a bit inconsistent (there are some tabs
which I left since I didn't touch those lines). Should I redo my patch
to get rid of them (adds some noise to the patch), keep them in a
separate patch (limited to this very function) or leave it as is?

Also, should I change MF_CreateMetaHeaderDisk to accept a LPCWSTR, even
though it then needs to convert it back to Ascii, or is the proposed way
sufficient?

Changelog:
Removed a W->A cross-call (CopyMetaFileW->CopyMetaFileA).

Vincent