Remove unwanted solution files from the repository.

Remove VC9-only solution files from a couple of tests/utils/demos (there is
no reason at all to have only VC9 solutions: either we have all of [789] or
none of them) and also remove all solutions files for the ribbon sample which
were probably added mistakenly in the first place (as no other sample has
them).

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@62469 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775