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

	* src/groups.c: Use a bool when possible instead of int integers.
	* src/groups.c: Add brackets and parenthesis.
	* src/groups.c: Avoid implicit conversion of pointers / integers
	to booleans.
	* src/groups.c: Avoid assignments in comparisons.
	* src/groups.c: Ignore the return value of putchar(), printf()
	* src/groups.c: Ignore return value of setlocale(),
	bindtextdomain(), and textdomain().