Fix Instances of Memory Corruption on Illumos

[AldaronLau]

In the future it would be nice to use libc (once an MSRV policy is decided on that's compatible with whoami 1.0's MSRV guarantees) or nix (in whoami 2.1), but for now doing a minimal patch.

Also, supporting Illumos as a tested target.

[AldaronLau]

Should fix #91

[sunshowers]

Thanks!

Just a couple of comments:

1. I don't think this catch-all should exist:

   whoami/src/os/unix.rs

   Lines 26 to 34 in d6ee13e

   	#[cfg(not(any(
   	target_os = "macos",
   	target_os = "freebsd",
   	target_os = "dragonfly",
   	target_os = "bitrig",
   	target_os = "openbsd",
   	target_os = "netbsd",
   	target_os = "illumos",
   	)))]

   . Instead, if a platform isn't known then it should fail to compile.
2. I think you can use libc 0.2 -- the MSRV for that won't change. It's just the MSRV for libc 1.0 that will change. If you do that, 1 is moot -- since you'll be pulling in all the definitions from libc.

Also, could you rename Illumos to illumos? It's always spelled with a lowercase "i" to avoid confusion between uppercase I and lowercase l.

[AldaronLau]

1. I don't think this catch-all should exist:

   whoami/src/os/unix.rs

   Lines 26 to 34 in d6ee13e

   	#[cfg(not(any(
   	target_os = "macos",
   	target_os = "freebsd",
   	target_os = "dragonfly",
   	target_os = "bitrig",
   	target_os = "openbsd",
   	target_os = "netbsd",
   	target_os = "illumos",
   	)))]

   
   . Instead, if a platform isn't known then it should fail to compile.

Yeah, I agree this should be reworked. I'll work on switching it for whoami 1.5.0, aiming to get that out today.

2. I think you can use libc 0.2 -- the MSRV for that won't change. It's just the MSRV for libc 1.0 that will change. If you do that, 1 is moot -- since you'll be pulling in all the definitions from libc.

This should be fine, will aim to get this change in for 1.6.0 since there's already a lot going into 1.5.0.

Also, could you rename Illumos to illumos? It's always spelled with a lowercase "i" to avoid confusion between uppercase I and lowercase l.

Where exactly should it be renamed? The platform enum should stay Illumos to match Rust casing guidelines. Just the README and Display implementation on Platform?

[sunshowers]

Yeah, readme, doc comments and Display impl. Thank you!