Changes

This project involves extending gcc to support an alwayszero function attribute (see [https://bugzilla.mozilla.org/show_bug.cgi?id=517370 Bug #517370] 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, ignoring the check.