Remove traces of previous update checker.
We use version 0.6.0 available here:
https://github.com/vslavik/winsparkle/releases
We only support on Windows at the moment using `winspakrle`. So remove
this item for other platforms or when disabled in compilation.
Signed-off-by: Rafael Kitover <rkitover@gmail.com>
Edênis Freindorfer Azevedo