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 bug44;

struct rgb
{
    long l;
}

void foo()
{
}

rgb test() {
  scope(exit) foo();
  return rgb();
}

void main()
{
    rgb r = test();
}