Add Android support for the i686 and x86-64 targets to the crash-context crate

[gabrielesvelto]

Checklist

• [✓] I have read the Contributor Guide
• [✓] I have read and agree to the Code of Conduct
• [✓] I have added a description of my changes and why I'd like them included in the section below

Description of Changes

This PR adds Android support for the i686 and x86-64 targets. This is largely used within emulators for testing. Note that I didn't add the architectures as supported in the top-level README.md file because I am still in the process of stabilizing Android support in the minidump-writer crate. Once that's done adding support within the crate should be trivial.

Related Issues

N/A

[gabrielesvelto]

The failure on macOS appears to be an issue with minidump-writer that has been potentially surfaced by new Rust versions. We're casting a pointer with a 4-bytes alignment into one that requires 8-bytes alignment. I'll file an issue and fix it.

[gabrielesvelto]

I prepared a PR to fix the failure here (here it is). @Jake-Shadle do you have some time to review this as well as rust-minidump/minidump-writer#81 ?

[Jake-Shadle]

Approved the other one, I think this is good to go since they are separate issues.