* src/newgrp.c: Use a bool for is_newgrp, notfound, needspasswd,

	* src/newgrp.c: Use a bool for is_newgrp, notfound, needspasswd,
	initflag, and cflag.
	* src/newgrp.c: Add brackets and parenthesis.
	* src/newgrp.c: Avoid implicit conversion of pointers / integers /
	chars to booleans.
	* src/newgrp.c: Avoid multi-statements lines.
	* src/newgrp.c: Ignore return value of setlocale(),
	bindtextdomain(), and textdomain().
	* src/newgrp.c: Avoid assignments in comparisons.