[C++,CMake] Increased minimum required GCC version to 4.9
[C++,CMake] Increased minimum required GCC version to 4.9

Change-Id: I7abd30a8967385a3a23c3204c2c414ee70c14e4d

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