Some `v128::{i8,u8}x16_ops_scalar_shifts` tests fail on AArch64

[JohnTitor]

Found in #315 (comment).

The failure is:

---- v128::i8x16_ops_scalar_shifts::ops_scalar_shifts stdout ----

thread 'v128::i8x16_ops_scalar_shifts::ops_scalar_shifts' panicked at 'assertion failed: `(left == right)`

  left: `i8x16(1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0)`,

 right: `i8x16(1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1)`', src/v128.rs:6:1

---- v128::i8x16_ops_vector_rotate::rotate_ops stdout ----

thread 'v128::i8x16_ops_vector_rotate::rotate_ops' panicked at 'assertion failed: `(left == right)`

  left: `i8x16(1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0)`,

 right: `i8x16(1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1)`', src/v128.rs:6:1

---- v128::i8x16_ops_vector_shifts::ops_vector_shifts stdout ----

thread 'v128::i8x16_ops_vector_shifts::ops_vector_shifts' panicked at 'assertion failed: `(left == right)`

  left: `i8x16(1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0)`,

 right: `i8x16(1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1)`', src/v128.rs:6:1

---- v128::u8x16_ops_scalar_shifts::ops_scalar_shifts stdout ----

thread 'v128::u8x16_ops_scalar_shifts::ops_scalar_shifts' panicked at 'assertion failed: `(left == right)`

  left: `u8x16(1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0)`,

 right: `u8x16(1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1)`', src/v128.rs:11:1

---- v128::u8x16_ops_vector_rotate::rotate_ops stdout ----

thread 'v128::u8x16_ops_vector_rotate::rotate_ops' panicked at 'assertion failed: `(left == right)`

  left: `u8x16(1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0)`,

 right: `u8x16(1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1)`', src/v128.rs:11:1

---- v128::u8x16_ops_vector_shifts::ops_vector_shifts stdout ----

thread 'v128::u8x16_ops_vector_shifts::ops_vector_shifts' panicked at 'assertion failed: `(left == right)`

  left: `u8x16(1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0)`,

 right: `u8x16(1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1)`', src/v128.rs:11:1

failures:

    v128::i8x16_ops_scalar_shifts::ops_scalar_shifts

    v128::i8x16_ops_vector_rotate::rotate_ops

    v128::i8x16_ops_vector_shifts::ops_vector_shifts

    v128::u8x16_ops_scalar_shifts::ops_scalar_shifts

    v128::u8x16_ops_vector_rotate::rotate_ops

    v128::u8x16_ops_vector_shifts::ops_vector_shifts

test result: FAILED. 2544 passed; 6 failed; 0 ignored; 0 measured; 0 filtered out; finished in 2.26s