dtfile makes use of ustat(2) on certain systems. This call has been
deprecated in glibc for a while and now, as of glibc-2.28, it has been
removed. The recommended replacement is to use statfs(2).
The libc.so file is not always in /usr/lib. On multilib systems, the
file we care about could be in /usr/lib64. Likewise, common Linux
conventions call for 64-bit libraries to go in lib64 directories, so
check there first when on a Linux 64-bit system.