entry validity before commits to databases.
* libmisc/fields.c, libmisc/Makefile.am, lib/fields.c,
lib/Makefile.am, po/POTFILES.in: fields.c moved from libmisc to
lib.
lib/prototypes.h: Move user_busy() to libmisc/user_busy.c.
* NEWS, libmisc/user_busy.c: On Linux, do not check if an user is
logged in with utmp, but check if the user is running some
processes. If not on Linux, continue to search for an utmp record,
but make sure the process recorded in the utmp entry is still
running.
