Fix faulty backport which broke the Windows build
Commit 91307842 inadvertently mangled the XML structure inside lib/isc/win32/libisc.vcxproj.filters.in, thus breaking the Windows build. Add the missing XML tags to make Windows builds work again.
Commit 91307842 inadvertently mangled the XML structure inside lib/isc/win32/libisc.vcxproj.filters.in, thus breaking the Windows build. Add the missing XML tags to make Windows builds work again.