Enable kernel sanitizers for aarch64-unknown-none-softfloat

We want kernels to be able to use this bare metal target, so
let's enable the sanitizers that kernels want to use.

compiler/rustc_target/src/spec/targets/aarch64_unknown_none_softfloat.rs

@@ -7,7 +7,8 @@
 // For example, `-C target-cpu=cortex-a53`.
 
 use crate::spec::{
-    Cc, LinkerFlavor, Lld, PanicStrategy, RelocModel, StackProbeType, Target, TargetOptions,
+    Cc, LinkerFlavor, Lld, PanicStrategy, RelocModel, SanitizerSet, StackProbeType, Target,
+    TargetOptions,
 };
 
 pub(crate) fn target() -> Target {
@@ -19,6 +20,7 @@ pub(crate) fn target() -> Target {
         relocation_model: RelocModel::Static,
         disable_redzone: true,
         max_atomic_width: Some(128),
+        supported_sanitizers: SanitizerSet::KCFI | SanitizerSet::KERNELADDRESS,
         stack_probes: StackProbeType::Inline,
         panic_strategy: PanicStrategy::Abort,
         ..Default::default()