[C++, Build] do not search for libjsmn.a in JoynrConfig.cmake.in
[C++, Build] do not search for libjsmn.a in JoynrConfig.cmake.in

this static library is not required when using libjoynr,
only the header must be present

Change-Id: I12ed9fdb4edc3901c41eb2bb9a4d752d5552ecdf

clive-jevons/joynr,clive-jevons/joynr,bmwcarit/joynr,bmwcarit/joynr,clive-jevons/joynr,bmwcarit/joynr,clive-jevons/joynr,bmwcarit/joynr,bmwcarit/joynr,clive-jevons/joynr,bmwcarit/joynr,bmwcarit/joynr,bmwcarit/joynr,bmwcarit/joynr,clive-jevons/joynr