iox-#252 removed non existing c++ callback example from cmake file
iox-#252 removed non existing c++ callback example from cmake file

Signed-off-by: Christian Eltzschig <5fe47766f2ae0978f8c0e6338f33674858b5ab51@de.bosch.com>

eclipse-iceoryx/iceoryx,eclipse-iceoryx/iceoryx,eclipse-iceoryx/iceoryx,eclipse-iceoryx/iceoryx