fix checking os_family

[RalfJung]

Cc rust-lang/rust#84848

[RalfJung]

@bors r+

[bors]

📌 Commit aac6e2a has been approved by RalfJung

[bors]

⌛ Testing commit aac6e2a with merge 44db1fd...

[bors]

💔 Test failed - checks-actions

[ghost]

error: unsupported operation: can't call foreign function: llvm.aarch64.isb
  --> /usr/share/rust/.rustup/toolchains/master/lib/rustlib/src/rust/library/core/src/../../stdarch/crates/core_arch/src/acle/barrier/common.rs:12:9
   |
12 |         super::isb(super::arg::SY)
   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^ can't call foreign function: llvm.aarch64.isb
   |
   = help: this is likely not a bug in the program; it indicates that the program performed an operation that the interpreter does not support
           
   = note: inside `<std::arch::aarch64::SY as core::core_arch::acle::sealed::Isb>::__isb` at /usr/share/rust/.rustup/toolchains/master/lib/rustlib/src/rust/library/core/src/../../stdarch/crates/core_arch/src/acle/barrier/common.rs:12:9
   = note: inside `std::arch::aarch64::__isb::<std::arch::aarch64::SY>` at /usr/share/rust/.rustup/toolchains/master/lib/rustlib/src/rust/library/core/src/../../stdarch/crates/core_arch/src/acle/barrier/mod.rs:122:5
   = note: inside `std::hint::spin_loop` at /usr/share/rust/.rustup/toolchains/master/lib/rustlib/src/rust/library/core/src/hint.rs:131:22
   = note: inside `std::sync::atomic::spin_loop_hint` at /usr/share/rust/.rustup/toolchains/master/lib/rustlib/src/rust/library/core/src/sync/atomic.rs:2790:5
note: inside `test_spin_loop_hint` at $DIR/sync_singlethread.rs:54:5
  --> $DIR/sync_singlethread.rs:54:5
   |
54 |     atomic::spin_loop_hint();
   |     ^^^^^^^^^^^^^^^^^^^^^^^^
note: inside `main` at $DIR/sync_singlethread.rs:8:5
  --> $DIR/sync_singlethread.rs:8:5
   |
8  |     test_spin_loop_hint();
   |     ^^^^^^^^^^^^^^^^^^^^^
   = note: inside `<fn() as std::ops::FnOnce<()>>::call_once - shim(fn())` at /usr/share/rust/.rustup/toolchains/master/lib/rustlib/src/rust/library/core/src/ops/function.rs:227:5

Probably due to rust-lang/rust#84725.

[RalfJung]

Yes that seems to be it, thanks for digging that out!
@bors r+

[bors]

📌 Commit c3ae8a6 has been approved by RalfJung

[bors]

⌛ Testing commit c3ae8a6 with merge 43ae314...

[bors]

☀️ Test successful - checks-actions
Approved by: RalfJung
Pushing 43ae314 to master...