/usr/share/doc/libmudflap0-4.7-dev-armel-cross is in libmudflap0-4.7-dev-armel-cross 4.7.3-1ubuntu1cross1.81.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/doc/gcc-4.7-arm-linux-gnueabi-base