* src/chage.c: EPOCH is not needed, it's converted to -1 by

	* src/chage.c: EPOCH is not needed, it's converted to -1 by
	strtoday(). But we need to support "-1" specifically.
	* src/chage.c: Fix usage: LOGIN is mandatory.
	* src/chage.c: Display disabled expiry or last change as "-1"
	instead of 1969-12-31. 1969-12-31 is still supported as input from
	the user.
	* src/chage.c: Exit cleanly with fail_exit() (lock files were not
	removed).