Properly fix alignment of bytes on stack

[phischu]

The following example still segfaults:

def foo { action: (Byte, Byte) => Unit }: Unit =
  action(42.toByte, 42.toByte)

def main() = {
  foo { (b0, b1) =>
    println(42)
    println(b0)
    println(b1)
  }
}

I see three solutions:

1. Undo the optimization and reserve stack space twice when pushing a frame: once for the environment and once for the header.
2. Change the definition of %Byte to i64 in llvm and hope for the best. This will require greate care in extern functions acting on bytes.
3. Insert getelementptr instructions to ask llvm to calculate the size of a frame for us.

Unsurprisingly I am for (1).