JNI: assert if the JavaVM cannot be found from a JNIEnv
JNI: assert if the JavaVM cannot be found from a JNIEnv

Change-Id: I0c6995e6c30ee23b396d564425e4c4f02731e5ab
Reviewed-on: http://gerrit.aldebaran.lan/77667
Reviewed-by: hcuche <2a0975cc082cedff4d4350e3f6ec187146151bc6@aldebaran.com>
Tested-by: vpaleologue <cb19838a79eb484e12a6960acfbf7c16dfdb80d9@aldebaran-robotics.com>

aldebaran/libqi-java,aldebaran/libqi-java,aldebaran/libqi-java