* lib/gshadow.c: Use a bool when possible instead of int integers.

	* lib/gshadow.c: Use a bool when possible instead of int integers.
	* lib/gshadow.c: Remove __setsgNIS() -never used).
	* lib/gshadow.c: Avoid multi-statements lines.
	* lib/gshadow.c: Avoid assignments in comparisons.
	* lib/gshadow.c: ptr[nelem] is a string. Initialize it to NULL
	instead of '\0'.
	* lib/gshadow.c: Add brackets and parenthesis.
	* lib/gshadow.c: The size argument of strncpy is a size_t and the
	size argument of fgets is an int.