UTMP is SVID legacy, UTMPX is mandated by POSIX.
Glibc and uClibc have identical layout of UTMP and UTMPX, both of these
libc treat _PATH_UTMPX as _PATH_UTMP so from a user-perspective nothing
changes except the names of the API entrypoints.
Signed-off-by: Bernhard Reutner-Fischer <rep.dot.nop@gmail.com>