hidl-gen: Fix nested type cannot be found.

Bug: 31821285

Test: `mma`
Test: `make hidl_test && adb sync && adb shell hidl_test`
Change-Id: I4a407e65973d85f76b43adff668155f15b783946
diff --git a/FQName.h b/FQName.h
index deb533b..b3e0002 100644
--- a/FQName.h
+++ b/FQName.h
@@ -33,6 +33,9 @@
            const std::string &name,
            const std::string &valueName = "");
 
+    // a synonym to FQName(names.join("."))
+    FQName(const std::vector<std::string> &names);
+
     FQName(const FQName& other);
 
     bool isValid() const;