Array init with 0i32 uses 0u32 instead

[LegNeato]

Migrated from EmbarkStudios/rust-gpu#1143

closes #85
original issue: EmbarkStudios/rust-gpu#1061

[149segolte]

@LegNeato Works. I haven't done extensive testing but the project I am working on does comppile with this. Previously I was using:

let mut seed_array = [1i32; 56];
for i in 0..56 {
    seed_array[i] = 0;
}

Now I am able to directly do: [0i32; 56].

[LegNeato]

Thanks @JulianKnodt for the original fix!

[Firestar99]

btw in compiletest you can put multiple entry points in a single file if you just want to check that they compile and not disassemble them
(feel free to change or merge)

[LegNeato]

Yeah, those were just the original tests and figure it doesn't hurt really.