Fix a bug where ::warning() was called with a va_list argument instead of an actual vararg list. Also cleaned up the format for warnings. (Previously some would start with "warning - warning - Warning:" which was a bit redundant)

module foreach4;
extern(C) int printf(char*, ...);
void main()
{
    int[] arr = new int[4];
    foreach(i,v;arr) {
        printf("arr[%u] = %d\n",i,v);
    }
}