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/Android.bp b/runtime/Android.bp
index 1ac770f..86cdc8b 100644
--- a/runtime/Android.bp
+++ b/runtime/Android.bp
@@ -544,6 +544,7 @@
         "base/bit_struct_test.cc",
         "base/bit_utils_test.cc",
         "base/bit_vector_test.cc",
+        "base/file_utils_test.cc",
         "base/hash_set_test.cc",
         "base/hex_dump_test.cc",
         "base/histogram_test.cc",
@@ -566,6 +567,7 @@
         "entrypoints/math_entrypoints_test.cc",
         "entrypoints/quick/quick_trampoline_entrypoints_test.cc",
         "entrypoints_order_test.cc",
+        "exec_utils_test.cc",
         "gc/accounting/card_table_test.cc",
         "gc/accounting/mod_union_table_test.cc",
         "gc/accounting/space_bitmap_test.cc",