ir: Plug a memory leak, when maturing a block without predecessors.
ir: Plug a memory leak, when maturing a block without predecessors.

jonashaag/libfirm,jonashaag/libfirm,jonashaag/libfirm,libfirm/libfirm,jonashaag/libfirm,MatzeB/libfirm,libfirm/libfirm,MatzeB/libfirm,libfirm/libfirm,jonashaag/libfirm,libfirm/libfirm,libfirm/libfirm,jonashaag/libfirm,MatzeB/libfirm,MatzeB/libfirm,MatzeB/libfirm,MatzeB/libfirm,jonashaag/libfirm,MatzeB/libfirm