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/reflection-inl.h b/runtime/reflection-inl.h
index 62ce9e9..6edb12f 100644
--- a/runtime/reflection-inl.h
+++ b/runtime/reflection-inl.h
@@ -22,6 +22,7 @@
 #include "android-base/stringprintf.h"
 
 #include "common_throws.h"
+#include "dex/descriptors_names.h"
 #include "jvalue-inl.h"
 #include "mirror/object-inl.h"
 #include "obj_ptr-inl.h"