Regioned destructors don't run in the right order

[bblum]

I believe the issue is simply that destructors are run in regardless order of borrows. Instead, the destructors with borrows should run first.

This code prints, rust: ~"bye \xffffff91"

class defer {
    x: &str;
    new(x: &str) { self.x = x; }
    drop { #error["%s", self.x]; }
}

fn main() {
    let _x = defer(~"Goodbye world!");
    #error["..."];
}

and this code segfaults:

class defer {
    x: &[&str];
    new(x: &[&str]) { self.x = x; }
    drop { #error["%?", self.x]; }
}

fn main() {
    let _x = defer(~["Goodbye", "world!"]);
}

[bblum]

Dup of #2977

[nikomatsakis]

This currently fails with "illegal borrow", as of ea549e7