swig: Update to version 2.0.12 and fix cmake find swig issue.

* Dropped PR and PR_INC due to PV change.
 * The cmake rule looks for swig2.0. For the sdk case, the host distro
may have a swig2.0 installed. If so the sdk would find the host swig. This
updates the sdk so it also has a swig2.0 soft linked to the swig binary in
the sdk.

Signed-off-by: Philip Balister <philip@balister.org>
Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>