Win32: replaced NGX_EXDEV with more appropriate error code.

Win32: replaced NGX_EXDEV with more appropriate error code.

Correct error code for NGX_EXDEV on Windows is ERROR_NOT_SAME_DEVICE,
"The system cannot move the file to a different disk drive".

Previously used ERROR_WRONG_DISK is about wrong diskette in the drive and
is not appropriate.

There is no real difference though, as MoveFile() is able to copy files
between disk drives, and will fail with ERROR_ACCESS_DENIED when asked
to copy directories.  The ERROR_NOT_SAME_DEVICE error is only used
by MoveFileEx() when called without the MOVEFILE_COPY_ALLOWED flag.