aarch64-apple-ios-sim target doesn't set cfg(target_env = "sim")

[jrose-signal]

I tried to identify iOS devices (not simulators) with the following cfg attribute:

#[cfg(all(target_os = "ios", target_arch = "aarch64", not(target_env = "sim")))

This is to distinguish the aarch64-apple-ios and aarch64-apple-ios-sim targets (the latter promoted to Tier 2 in #87760). Unfortunately, target_env = "sim" isn't set for aarch64-apple-ios-sim, making them identical as far as the built-in cfg options go.

This isn't the end of the world because I can test the full target in build.rs, but it is a little frustrating.

Bonus: it would be nice™ to set target_env = "sim" for x86_64-apple-ios as well, which is also a simulator target. It historically didn't have -sim in its canonical form because Apple never made Intel iPhones, but it would be great to drop the target_arch condition altogether (especially if #115526 ends up changing the target_arch).

[jrose-signal]

cc @badboy, @deg4uss3r per the Platform Support page for aarch64-apple-ios-sim

[jrose-signal]

*facepalm* It is exposed in the target_abi. So maybe this is just a docs bug.

[jrose-signal]

Never mind, off to comment on #80970…