Type inference error when running on simplicity-sys backend

[m-kus]

The following Simfony program results in an invalid script rejected by the Elements node:

fn main() {
    let (a, b): (u32, u32) = (0, 1);
    assert!(jet::eq_32(a, 0));

    let (c, d): (u32, u32) = (2, 3);
    assert!(jet::eq_32(c, 2));
    assert!(jet::eq_32(d, 3));
}

Corresponding program hex:

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

Although it runs without errors on BitMachine (after fixes from #116) the simplicity_mallocTypeInference yields SIMPLICITY_ERR_TYPE_INFERENCE_UNIFICATION.

#117 demonstrates how to reproduce the issue.