Fix debug representation of arrays of structs

[jdm]

"Up-to-date" test case:

fn main() {
    struct moo {a: float};
    let x = [moo{a: 1.5}, moo{a: 2.3}];
    io::println(fmt!("%?", x));
}

(build with rustc -Z debug-info, then load it up in gdb and set a breakpoint on main.)

Original reported test case follows

let x = [{a: 1.5},{a: 2.3}]

The values of a in gdb are wildly incorrect.

[marijnh]

Objs are no longer with us.

[jdm]

This was a poorly worded issue.

[catamorphism]

(And if that doesn't work, I bet debug representations of classes don't work either :-)

[pnkfelix]

This is blocked by Issue #5836

[huonw]

Triage visit: #5836 is closed, @michaelwoerister has done amazing work, and this is fixed!

fn main() {
    struct moo {a: float};
    let x = [moo{a: 1.5}, moo{a: 2.3}];
    printfln!("%?", x);
}

$ rustc -Z debug-info -Z extra-debug-info 1340.rs

(gdb) break 4
[...]
(gdb) r
[...]
(gdb) p x
$1 = {{a = 1.5}, {a = 2.2999999999999998}}