[C++, Build] set default log level depending on build type
[C++, Build] set default log level depending on build type

For DEBUG builds, the log level is set to TRACE.
For every other build type the default log level is set to ERROR

Change-Id: Ib87068d36795aba862b1dc88ceff9f6d778f7b1a

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