Makefile-newvs: some .vcxproj.filters files are in builddir, some in srcdir

Makefile-newvs: some .vcxproj.filters files are in builddir, some in srcdir

Without this change, out-of-tree distcheck doesn't get very far.

Similarly, allow *.vcxproj, *.props to be in either the builddir or
the srcdir.

Finally, since I'm touching these lines anyway, eliminate some
useless uses of cat: "cat x | sed 's/foo/bar/' > y" is
equivalent to "sed 's/foo/bar/' < x > y".

Bug: https://bugzilla.gnome.org/show_bug.cgi?id=748176
Reviewed-by: Chun-wei Fan <fanchunwei@src.gnome.org>