For years the man pages have said to #include <sys/types.h> to get

For years the man pages have said to #include <sys/types.h> to get
major/minor/makedev, but glibc has vowed to break existing programs
(https://sourceware.org/ml/libc-alpha/2015-11/msg00253.html)
and replace it with _another_ non-standard header (not in posix or lsb),
so let's just add functions to lib/ that do the transform ourselves.