directory-prefix bug in Win32

[Denis Golovan]

Hi!

  When using -P or --directory-prefix in v1.11 Beta 1 and later v1.11 Beta 
1(with spider patch) command-line
switches wget does not pay attention to neither of them. It saves files in 
the current directory. Wget v1.10.2 worked right.
  Hope, this bug won't live long :).