Add illumos aarch64 target for rust.

Signed-off-by: Till Wegmueller <toasterson@gmail.com>

compiler/rustc_target/src/spec/aarch64_unknown_illumos.rs

@@ -0,0 +1,19 @@
+use crate::spec::{Cc, LinkerFlavor, SanitizerSet, Target};
+
+pub fn target() -> Target {
+    let mut base = super::illumos_base::opts();
+    base.add_pre_link_args(LinkerFlavor::Unix(Cc::Yes), &["-std=c99"]);
+    base.cpu = "aarch64".into();
+    base.max_atomic_width = Some(128);
+    base.supported_sanitizers = SanitizerSet::ADDRESS | SanitizerSet::CFI;
+
+    Target {
+        // LLVM does not currently have a separate illumos target,
+        // so we still pass Solaris to it
+        llvm_target: "aarch64-unknown-solaris2.11".into(),
+        pointer_width: 64,
+        data_layout: "e-m:e-i8:8:32-i16:16:32-i64:64-i128:128-n32:64-S128".into(),
+        arch: "aarch64".into(),
+        options: base,
+    }
+}

compiler/rustc_target/src/spec/mod.rs

@@ -1407,6 +1407,7 @@ supported_targets! {
     ("sparcv9-sun-solaris", sparcv9_sun_solaris),
 
     ("x86_64-unknown-illumos", x86_64_unknown_illumos),
+    ("aarch64-unknown-illumos", aarch64_unknown_illumos),
 
     ("x86_64-pc-windows-gnu", x86_64_pc_windows_gnu),
     ("i686-pc-windows-gnu", i686_pc_windows_gnu),