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/native/java_lang_VMClassLoader.cc b/runtime/native/java_lang_VMClassLoader.cc
index 6eebff4..3a0d760 100644
--- a/runtime/native/java_lang_VMClassLoader.cc
+++ b/runtime/native/java_lang_VMClassLoader.cc
@@ -17,6 +17,7 @@
 #include "java_lang_VMClassLoader.h"
 
 #include "class_linker.h"
+#include "dex/descriptors_names.h"
 #include "dex/dex_file_loader.h"
 #include "jni_internal.h"
 #include "mirror/class_loader.h"