* src/useradd.c: Use a bool when possible instead of int integers.

	* src/useradd.c: Use a bool when possible instead of int integers.
	* src/useradd.c: Avoid implicit conversion of pointers / integers
	/ chars to booleans.
	* src/useradd.c: Add brackets and parenthesis.
	* src/useradd.c: Avoid assignments in comparisons.
	* src/useradd.c: Ignore the return value of fclose() for read-only
	files.
	* src/useradd.c: Ignore the return value of fflush() before
	closing the files.
	* src/useradd.c: Avoid multi-statements lines.
	* src/useradd.c: Ignore return value of setlocale(),
	bindtextdomain(), and textdomain().
	* src/useradd.c: Ignore the return value of pam_end() before
	exiting.