ref: 6db6735df5f0e8d44c591c0ff8130c47f94c5d37
parent: 10b54e590ef8bfd54c5dc9712d0864db4be4e1ce
author: Ori Bernstein <ori@eigenstate.org>
date: Mon Dec 16 11:48:38 EST 2013
Convert main() to effectively return void.
Now, if we exit thorugh the end of main, we will ignore
the return value, and call exit(0) from the start stub.
If you want to exit with a different return value, you need
to call std.exit(val)