COMP: fix swig build to match SimpleITK

Use the same version and url that are known to work in SimpleITK's
superbuild.

Note: also remove "${${PROJECT_NAME}_EP_DISABLED_UPDATE}" and replace
it with UPDATE_COMMAND "" as I believe this gives the same effect and
avoids confusion about the intent. More importantly, on windows
the empty cmake argument led to the addition of a semicolon to the
directory name (so it became "swigwin-2.0.9;") which was ugly and
confusing.

git-svn-id: http://svn.slicer.org/Slicer4/trunk@22084 3bd1e089-480b-0410-8dfb-8563597acbee