Fix a miscompile for s390x with constants

This carries over a narrow fix from bytecodealliance#4427 to prior release branches. The
patch here was created by `@uweigand` during the investigation for bytecodealliance#4487.

cranelift/codegen/src/isa/s390x/lower/isle.rs

@@ -226,7 +226,8 @@ where
     fn u64_from_value(&mut self, val: Value) -> Option<u64> {
         let inst = self.lower_ctx.dfg().value_def(val).inst()?;
         let constant = self.lower_ctx.get_constant(inst)?;
-        Some(constant)
+        let ty = self.lower_ctx.output_ty(inst, 0);
+        Some(zero_extend_to_u64(constant, self.ty_bits(ty).unwrap()))
     }
 
     #[inline]
@@ -516,3 +517,14 @@ where
         self.lower_ctx.emit(inst.clone());
     }
 }
+
+/// Zero-extend the low `from_bits` bits of `value` to a full u64.
+#[inline]
+fn zero_extend_to_u64(value: u64, from_bits: u8) -> u64 {
+    assert!(from_bits <= 64);
+    if from_bits >= 64 {
+        value
+    } else {
+        value & ((1u64 << from_bits) - 1)
+    }
+}