Unbreak non-x86 build on FreeBSD

[ghost]

error[E0432]: unresolved import `self::arm::check_for`
  --> src/libstd/../stdarch/crates/std_detect/src/detect/os/freebsd/mod.rs:11:17
   |
11 |         pub use self::arm::check_for;
   |                 ^^^^^^^^^^^^^^^^^^^^ no `check_for` in `std_detect::detect::os::arm`

error[E0425]: cannot find value `detect_features` in module `self::os`
   --> src/libstd/../stdarch/crates/std_detect/src/detect/mod.rs:121:37
    |
121 |     cache::test(x as u32, self::os::detect_features)
    |                                     ^^^^^^^^^^^^^^^ not found in `self::os`
    |
help: possible candidate is found in another module, you can import it into scope
    |
20  | use crate::std_detect::detect::os::arm::detect_features;

Regressed by: 9fad964
Found during Rust 1.43.0 package update: https://reviews.freebsd.org/D24521
Submitted by: @MikaelUrankar

[rust-highfive]

r? @gnzlbg

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[Amanieu]

Does this need to be backported to stable?

[ghost]

Thanks. We patched it locally, but it would be nice if we could drop this patch again when Rust 1.44.0 (or 1.43.1 if there is one) is released.