fix: remove unused asm_experimental_arch feature

Cargo.toml

@@ -246,7 +246,6 @@ check-cfg = [
     'cfg(alloc_c_string)',
     'cfg(alloc_ffi)',
     'cfg(apple)',
-    'cfg(asm_experimental_arch)',
     'cfg(bsd)',
     'cfg(core_c_str)',
     'cfg(core_ffi_c)',

build.rs

@@ -127,9 +127,6 @@ fn main() {
         // Use the linux_raw backend.
         use_feature("linux_raw_dep");
         use_feature("linux_raw");
-        if rustix_use_experimental_asm {
-            use_feature("asm_experimental_arch");
-        }
     }
 
     // Detect whether the compiler requires us to use thumb mode on ARM.

src/lib.rs

@@ -114,7 +114,6 @@
     any(feature = "rustc-dep-of-std", core_intrinsics),
     feature(core_intrinsics)
 )]
-#![cfg_attr(asm_experimental_arch, feature(asm_experimental_arch))]
 #![cfg_attr(not(feature = "all-apis"), allow(dead_code))]
 // It is common in Linux and libc APIs for types to vary between platforms.
 #![allow(clippy::unnecessary_cast)]