Input/output statements in functions other than main for ABY backend

[nishkum]

Consider this code:

def uint32_al foo(){
  input(CLIENT, y, uint32_al);
  return y;
}

def void bar(uint32_al x){
  output(ALL, x);
}

def void main(){
  uint32_al x = foo();
  bar(x);
}

When compiled with ABY backend, ezpc compiles fine - but ABY itself doesn't compile.
This is because input/output statements use a variable called role, which is currently only being defined in main - if used in other functions, it results in error.
A solution can be to define role as a global variable and assign it in main.

[nishkum]

Fixed in #6 - closing the issue.