/usr/share/man/man1/mips64el-linux-gnuabin32-c++filt.1.gz is in binutils-mips64el-linux-gnuabin32 2.30-15ubuntu1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/man/man1/c++filt.1.gz
/usr/share/man/man1/c++filt.1.gz