Reland: Make clusterfuzz_archive include llvm-symbolizer and sancov.

scripts/slave/recipe_modules/archive/example.expected/cf_archiving_svn_no_git.json

 [
   {
     "cmd": [
       "python",
       "-u",
+      "\nimport shutil\nimport sys\nshutil.copy(sys.argv[1], sys.argv[2])\n",
+      "None/third_party/llvm-build/Release+Asserts/bin/llvm-symbolizer",
+      "[SLAVE_BUILD]/src/out/Release/llvm-symbolizer"
+    ],
+    "name": "Copy llvm-symbolizer"
+  },
+  {
+    "cmd": [
+      "python",
+      "-u",
+      "\nimport shutil\nimport sys\nshutil.copy(sys.argv[1], sys.argv[2])\n",
+      "None/third_party/llvm-build/Release+Asserts/bin/sancov",
+      "[SLAVE_BUILD]/src/out/Release/sancov"
+    ],
+    "name": "Copy sancov"
+  },
+  {
+    "cmd": [
+      "python",
+      "-u",
       "\nimport json, os, sys\nif os.path.exists(sys.argv[1]) and os.path.isdir(sys.argv[1]):\n  with open(sys.argv[2], 'w') as f:\n    json.dump(os.listdir(sys.argv[1]), f)\n",
       "[SLAVE_BUILD]/src/out/Release",
       "/path/to/tmp/json"
     ],
     "name": "listdir build_dir",
     "~followup_annotations": [
       "@@@STEP_LOG_LINE@json.output@[@@@",
       "@@@STEP_LOG_LINE@json.output@  \"chrome\"@@@",
       "@@@STEP_LOG_LINE@json.output@]@@@",
       "@@@STEP_LOG_END@json.output@@@",
@@ skipping 51 matching lines @@
       "@@@STEP_LOG_LINE@python.inline@os.remove(sys.argv[1])@@@",
       "@@@STEP_LOG_END@python.inline@@@"
     ]
   },
   {
     "name": "$result",
     "recipe_result": null,
     "status_code": 0
   }
 ]