allow aarch64_softfloat_neon for backwards compatibility

Author: RalfJung

library/stdarch/crates/core_arch/src/aarch64/mod.rs

@@ -6,6 +6,13 @@
 //! [arm_ref]: http://infocenter.arm.com/help/topic/com.arm.doc.ihi0073a/IHI0073A_arm_neon_intrinsics_ref.pdf
 //! [arm_dat]: https://developer.arm.com/technologies/neon/intrinsics
 
+#![cfg_attr(
+    all(target_arch = "aarch64", target_abi = "softfloat"),
+    // Just allow the warning: anyone soundly using the intrinsics has to enable
+    // the target feature, and that will generate a warning for them.
+    allow(aarch64_softfloat_neon)
+)]
+
 mod mte;
 #[unstable(feature = "stdarch_aarch64_mte", issue = "129010")]
 pub use self::mte::*;

library/stdarch/crates/core_arch/src/arm_shared/mod.rs

@@ -47,6 +47,12 @@
 //!
 //! - [ACLE Q2 2018](https://developer.arm.com/docs/101028/latest)
 
+#![cfg_attr(
+    all(target_arch = "aarch64", target_abi = "softfloat"),
+    // Just allow the warning: anyone soundly using the intrinsics has to enable
+    // the target feature, and that will generate a warning for them.
+    allow(aarch64_softfloat_neon)
+)]
 // Only for 'neon' submodule
 #![allow(non_camel_case_types)]