Test: Fix solarish_tap test on big-endian targets

[joshuaissac]

What does this PR do

This change corrects the solarish_tap test on big-endian Solaris targets.

The two changes are to populate multi-byte numbers in the byte array using the native endianness (previous code assumed little-endianness), and to use a buffer that guarantees the required alignment when taking a pointer to it (previous code guaranteed only 1-byte alignment).

Tested on Solaris 11.4 (SPARC 64-bit).

Checklist:

• I have read CONTRIBUTING.md
• I have written necessary tests and rustdoc comments
• A change log has been added if this PR modifies nix's API

[joshuaissac]

Check i686-unknown-linux-musl failing due to unrelated reason:

docker: failed to copy: httpReadSeeker: failed open: failed to do request: Get "https://ghcr.io/v2/cross-rs/i686-unknown-linux-musl/blobs/sha256:8db86b1b7e4e0172fc34ed0a051c46a56ff9d90065ea000c332b2442e012af82": EOF

[asomers]

The test change looks good. But I request that you remove the changelog entry. This change isn't visible to our crate's consumers, so it doesn't need to be mentioned in the changelog.

[joshuaissac]

The test change looks good. But I request that you remove the changelog entry. This change isn't visible to our crate's consumers, so it doesn't need to be mentioned in the changelog.

@asomers Changelog entry removed.