Fix trailing comma breaking array init vectors

This patch fixes a bug in commit d23e03e "Allow trailing comma in array
initializers" where initarray() did an extra loop iteration hoping that
initvector() would fail nicely and ultimately inserted an extra cell
into the literal queue.

--------- test code --------

native printf(const format[], ...);

new const a[][] = {
	{"hello"},
	{"world"}
};

main() {
	printf("%s", a[0]);          // hello
	printf("%d", sizeof(a));     // 2
	printf("%d", sizeof(a[]));   // 6
	printf("%d", sizeof(a[][])); // 1
}

----- end of test code -----