Enable the simd_i16x8_q15mulr_sat_s test on AArch64

Copyright (c) 2021, Arm Limited.

cranelift/interpreter/src/step.rs

@@ -574,6 +574,7 @@ where
         Opcode::AtomicStore => unimplemented!("AtomicStore"),
         Opcode::Fence => unimplemented!("Fence"),
         Opcode::WideningPairwiseDotProductS => unimplemented!("WideningPairwiseDotProductS"),
+        Opcode::SqmulRoundSat => unimplemented!("SqmulRoundSat"),
 
         // TODO: these instructions should be removed once the new backend makes these obsolete
         // (see https://github.com/bytecodealliance/wasmtime/issues/1936); additionally, the