Chromium-recipe: add rmtree before copy for llvm_tools_to_copy.

scripts/slave/recipes/chromium.expected/full_chromium_lkgr_TSAN_Debug.json

 [
   {
     "cmd": [
       "python",
       "-u",
       "\nimport sys, os\npath = sys.argv[1]\nmode = int(sys.argv[2])\nif not os.path.isdir(path):\n  if os.path.exists(path):\n    print \"%s exists but is not a dir\" % path\n    sys.exit(1)\n  os.makedirs(path, mode)\n",
       "[BUILDER_CACHE]/TSAN_Debug",
       "511"
     ],
     "name": "makedirs checkout path",
@@ skipping 303 matching lines @@
     "name": "compile",
     "~followup_annotations": [
       "@@@STEP_LOG_LINE@json.output (invalid)@null@@@",
       "@@@STEP_LOG_END@json.output (invalid)@@@"
     ]
   },
   {
     "cmd": [
       "python",
       "-u",
+      "\nimport os, sys\nfrom common import chromium_utils # Error? See https://crbug.com/584783.\n\n\nif os.path.exists(sys.argv[1]):\n  chromium_utils.RemoveDirectory(sys.argv[1])\n",
+      "[BUILDER_CACHE]/TSAN_Debug/src/out/Debug/llvm-symbolizer"
+    ],
+    "name": "rmtree Purge llvm-symbolizer",
+    "~followup_annotations": [
+      "@@@STEP_LOG_LINE@python.inline@@@@",
+      "@@@STEP_LOG_LINE@python.inline@import os, sys@@@",
+      "@@@STEP_LOG_LINE@python.inline@from common import chromium_utils # Error? See https://crbug.com/584783.@@@",
+      "@@@STEP_LOG_LINE@python.inline@@@@",
+      "@@@STEP_LOG_LINE@python.inline@@@@",
+      "@@@STEP_LOG_LINE@python.inline@if os.path.exists(sys.argv[1]):@@@",
+      "@@@STEP_LOG_LINE@python.inline@  chromium_utils.RemoveDirectory(sys.argv[1])@@@",
+      "@@@STEP_LOG_END@python.inline@@@"
+    ]
+  },
+  {
+    "cmd": [
+      "python",
+      "-u",
+      "\nimport shutil\nimport sys\nshutil.copy(sys.argv[1], sys.argv[2])\n",
+      "[BUILDER_CACHE]/TSAN_Debug/src/third_party/llvm-build/Release+Asserts/bin/llvm-symbolizer",
+      "[BUILDER_CACHE]/TSAN_Debug/src/out/Debug"
+    ],
+    "name": "Copy llvm-symbolizer"
+  },
+  {
+    "cmd": [
+      "python",
+      "-u",
+      "\nimport os, sys\nfrom common import chromium_utils # Error? See https://crbug.com/584783.\n\n\nif os.path.exists(sys.argv[1]):\n  chromium_utils.RemoveDirectory(sys.argv[1])\n",
+      "[BUILDER_CACHE]/TSAN_Debug/src/out/Debug/sancov"
+    ],
+    "name": "rmtree Purge sancov",
+    "~followup_annotations": [
+      "@@@STEP_LOG_LINE@python.inline@@@@",
+      "@@@STEP_LOG_LINE@python.inline@import os, sys@@@",
+      "@@@STEP_LOG_LINE@python.inline@from common import chromium_utils # Error? See https://crbug.com/584783.@@@",
+      "@@@STEP_LOG_LINE@python.inline@@@@",
+      "@@@STEP_LOG_LINE@python.inline@@@@",
+      "@@@STEP_LOG_LINE@python.inline@if os.path.exists(sys.argv[1]):@@@",
+      "@@@STEP_LOG_LINE@python.inline@  chromium_utils.RemoveDirectory(sys.argv[1])@@@",
+      "@@@STEP_LOG_END@python.inline@@@"
+    ]
+  },
+  {
+    "cmd": [
+      "python",
+      "-u",
+      "\nimport shutil\nimport sys\nshutil.copy(sys.argv[1], sys.argv[2])\n",
+      "[BUILDER_CACHE]/TSAN_Debug/src/third_party/llvm-build/Release+Asserts/bin/sancov",
+      "[BUILDER_CACHE]/TSAN_Debug/src/out/Debug"
+    ],
+    "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",
       "[BUILDER_CACHE]/TSAN_Debug/src/out/Debug",
       "/path/to/tmp/json"
     ],
     "name": "listdir build_dir",
     "~followup_annotations": [
       "@@@STEP_LOG_LINE@json.output@[@@@",
       "@@@STEP_LOG_LINE@json.output@  \"file 1\", @@@",
       "@@@STEP_LOG_LINE@json.output@  \"file 2\"@@@",
       "@@@STEP_LOG_LINE@json.output@]@@@",
@@ skipping 56 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
   }
 ]