Avoid calling memcpy with null pointer as source.
Avoid calling memcpy with null pointer as source.

Such a memcpy call results in undefined behavior.

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