AAPT2: Fix fully qualified java class verification

Proguard rules would be ignored for components defined
in AndroidManifest.xml for android:name attributes if
they didn't start with '.'.

Change-Id: I029b5a2f224f4daf155b73a2a4dcd940dd43372e
diff --git a/tools/aapt2/util/Util.cpp b/tools/aapt2/util/Util.cpp
index 7b0c71d..5748a12 100644
--- a/tools/aapt2/util/Util.cpp
+++ b/tools/aapt2/util/Util.cpp
@@ -175,11 +175,11 @@
         return {};
     }
 
+    std::u16string result(package.data(), package.size());
     if (className.data()[0] != u'.') {
-        return {};
+        result += u'.';
     }
 
-    std::u16string result(package.data(), package.size());
     result.append(className.data(), className.size());
     if (!isJavaClassName(result)) {
         return {};