* NEWS, src/newusers.c: Implement the -r, --system option.

	* NEWS, src/newusers.c: Implement the -r, --system option.
	* src/newusers.c: Use a bool when possible instead of int
	integers.
	* src/newusers.c: Avoid implicit conversion of pointers / integers
	/ chars to booleans.
	* src/newusers.c: Ignore the return value of pam_end() before
	exiting.
	* src/newusers.c: Ignore return value of setlocale(),
	bindtextdomain(), and textdomain().
	* src/newusers.c: Avoid multi-statements lines.
	* src/newusers.c: Add brackets and parenthesis.