Changes

This project involves extending gcc to support an alwayszero function attribute (see [https://bugzilla.mozilla.org/show_bug.cgi?id=517370 Bug #517370] as well as [[http://ehren.wordpress.com/2009/09/30/popping-my-gimples-a-plan/ this blog post]] for an overview). Essentially, a call to an alwayszero function foo in such contexts as if (foo() != 0) or while (foo() != 0) should completely ignore the test and automatically branch to the next statement upon return of the function.