Win: Build Glave replay on Windows (REQUIRES NEW CMAKE COMMAND).

Win: Build Glave replay on Windows (REQUIRES NEW CMAKE COMMAND).

Starting with this commit, building XGL on Windows requires explicitly stating
whether a "Release" or "Debug" build is desired when doing the initial cmake
command.  This is documented in the "Build.md" file.

Linux trace of cube plays to completion on windows!

Changes to the null driver:
    advertise support for both WIN WSI and X11 WSI
    added support for xglCreateBufferView
    and added a logging capability (turned off by default)

Still have some issues:
    - x11 support emulation/replacement
    - Windows null driver creates a bad device queue
    - Need to copy libraries to dir containing the .exe

Glave ext libs are now put in same dir as glvreplay64.exe...

This change only affects Windows -- on Linux the libs and
the glave replay progs were already in the same dir.

Also added a line to BUILD.md regarding the need to have XGL.dll
in PATH.