CMake: install cbc symlinks on non-windows platforms

Change-Id: I4ce1331d8cfcc60f86933be147f9a8fc30ec7fac
Reviewed-on: http://review.couchbase.org/42789
Reviewed-by: Sergey Avseyev <sergey.avseyev@gmail.com>
Tested-by: Mark Nunberg <mnunberg@haskalah.org>