* src/useradd.c: Remove def_file. It was always set to
USER_DEFAULTS_FILE.
* src/useradd.c: Fix cut&paste issue causing bad warning when
the useradd.default file contains an invalid INACTIVE= value.
* src/useradd.c: Added missing end of line for rename errors.
* src/useradd.c: Added -D synopsis to the usage message.
* src/useradd.c: Do not scale_age(-1), just use -1.
* src/useradd.c: Added FIXME to be fixed later.
* src/useradd.c: Allow -e -1 when there is no shadow file.
* src/useradd.c: Fail, but do not print the usage message when the
-e argument is not valid.
* src/useradd.c: No need to check for oflg since uflg is
already checked.