Removed unused friend classes for tests.

Change-Id: I7f08b0cd4abbbc82f329a8bec0d0994327b6dba9
diff --git a/runtime/base/mutex.h b/runtime/base/mutex.h
index 21ba0d2..2f41bcd 100644
--- a/runtime/base/mutex.h
+++ b/runtime/base/mutex.h
@@ -179,7 +179,6 @@
   const bool recursive_;  // Can the lock be recursively held?
   unsigned int recursion_count_;
   friend class ConditionVariable;
-  friend class MutexTester;
   DISALLOW_COPY_AND_ASSIGN(Mutex);
 };
 
@@ -290,7 +289,6 @@
 #else
   pthread_rwlock_t rwlock_;
 #endif
-  friend class MutexTester;
   DISALLOW_COPY_AND_ASSIGN(ReaderWriterMutex);
 };
 
diff --git a/runtime/class_linker.h b/runtime/class_linker.h
index 060c26c..67be2ff 100644
--- a/runtime/class_linker.h
+++ b/runtime/class_linker.h
@@ -617,9 +617,7 @@
   const void* portable_resolution_trampoline_;
   const void* quick_resolution_trampoline_;
 
-  friend class CommonTest;
   friend class ImageWriter;  // for GetClassRoots
-  friend class ObjectTest;
   FRIEND_TEST(ClassLinkerTest, ClassRootDescriptors);
   FRIEND_TEST(mirror::DexCacheTest, Open);
   FRIEND_TEST(ExceptionTest, FindExceptionHandler);