Fix leak in aidl_unittests

Turning on "sanitizer: address" revealed the leak in the test code.

Bug: n/a
Test: aidl_unittests
Change-Id: Id13820cff676d998934d6b1485d453f37397d696
diff --git a/aidl_unittest.cpp b/aidl_unittest.cpp
index efad030..782e150 100644
--- a/aidl_unittest.cpp
+++ b/aidl_unittest.cpp
@@ -1451,7 +1451,7 @@
 
   auto set_nullable = [](std::unique_ptr<AidlTypeSpecifier>&& type) {
     std::vector<AidlAnnotation> annotations;
-    annotations.emplace_back(*AidlAnnotation::Parse(AIDL_LOCATION_HERE, "nullable", nullptr, {}));
+    annotations.emplace_back(*AidlAnnotation::Parse(AIDL_LOCATION_HERE, "nullable", {}, {}));
     type->Annotate(std::move(annotations));
     return std::move(type);
   };