Build libxxavacore library for gtests

It is a dependency for exception_test, jni_compiler_test,
reflection_test and stub_test.

Change-Id: I0a4ed85762091617842901f9bd590d24fe39ec7b
diff --git a/runtime/runtime.cc b/runtime/runtime.cc
index d4917a3..61f75f4 100644
--- a/runtime/runtime.cc
+++ b/runtime/runtime.cc
@@ -1140,7 +1140,7 @@
   // Then set up the native methods provided by the runtime itself.
   RegisterRuntimeNativeMethods(env);
 
-  // Then set up libjavacore / libflavacore, which are just a regular JNI libraries with
+  // Then set up libjavacore / libxxavacore, which are just a regular JNI libraries with
   // a regular JNI_OnLoad. Most JNI libraries can just use System.loadLibrary, but
   // libcore can't because it's the library that implements System.loadLibrary!
   {