Remove duplication, split tests

The code move to libdexfile/dex/descriptors_names.cc apparently did not
remove the original code from runtime/utils.cc.  Fix that duplication
and all the header mentions needed.  Also, split the test files to go
along with the new locations for the code to be tested.

Bug: 22322814
Test: make -j 50 checkbuild
      make -j 50 test-art-host-gtest
      flash & boot marlin

Change-Id: Ie734672c4bca2c647d8016291f910b5608674545
diff --git a/runtime/interpreter/unstarted_runtime_test.cc b/runtime/interpreter/unstarted_runtime_test.cc
index 0986005..fd43562 100644
--- a/runtime/interpreter/unstarted_runtime_test.cc
+++ b/runtime/interpreter/unstarted_runtime_test.cc
@@ -24,6 +24,7 @@
 #include "base/memory_tool.h"
 #include "class_linker.h"
 #include "common_runtime_test.h"
+#include "dex/descriptors_names.h"
 #include "dex/dex_instruction.h"
 #include "handle.h"
 #include "handle_scope-inl.h"