CallJavaNode::_bci is not in use

The member variable CallJavaNode::_bci is completely dead in release build.

In debug builds, CallJavaNode::validate_symbolic_info does refer to it, but the information can obtain from jvms()->bci().
  ciMethod* symbolic_info = jvms()->method()->get_method_at_bci(_bci);

It also copies to MachCallJavaNode, but CodeGen doesn't use it as well.