lit-test: fix devirtualization/*.

lit-test/test/devirtualization/device_db.pyon

@@ -4,5 +4,11 @@
         "module": "artiq.coredevice.comm_dummy",
         "class": "Comm",
         "arguments": {}
+    },
+    "core": {
+        "type": "local",
+        "module": "artiq.coredevice.core",
+        "class": "Core",
+        "arguments": {"ref_period": 1e-9}
     }
 }

lit-test/test/devirtualization/function.py

@@ -4,7 +4,7 @@
 from artiq.language.core import *
 from artiq.language.types import *
 
-# CHECK-L: call ()->NoneType %local.testbench.entrypoint ; calls testbench.entrypoint
+# CHECK-L: call ()->NoneType delay('b) %local.testbench.entrypoint ; calls testbench.entrypoint
 
 @kernel
 def baz():