cranelift: Add inline stack probing for x64 (#4747)

* cranelift: Add inline stack probe for x64

* cranelift: Cleanups comments

Thanks @jameysharp!

cranelift/codegen/src/isa/aarch64/abi.rs

@@ -610,6 +610,10 @@ impl ABIMachineSpec for AArch64MachineDeps {
         smallvec![]
     }
 
+    fn gen_inline_probestack(_frame_size: u32, _guard_size: u32) -> SmallInstVec<Self::I> {
+        unimplemented!("Inline stack probing is unimplemented on AArch64");
+    }
+
     // Returns stack bytes used as well as instructions. Does not adjust
     // nominal SP offset; abi generic code will do that.
     fn gen_clobber_save(