Use symbol server DLLs of WinDbg

During installation, copy the symbol server DLLs of Debugging Tools for
Windows (WinDbg) to the location of the PyKd extension DLL to ensure
that these DLLs are used instead of the corresponding versions in
%WINDIR%\System32.
This is necessary as the pre-installed versions have restricted
functionality compared to the WinDbg DLLs.