Update V8 DEPS.

DEPS

 # Note: The buildbots evaluate this file with CWD set to the parent
 # directory and assume that the root of the checkout is in ./v8/, so
 # all paths in here must match this assumption.
 
 vars = {
   "git_url": "https://chromium.googlesource.com",
 }
 
 deps = {
   "v8/build/gyp":
     Var("git_url") + "/external/gyp.git" + "@" + "5122240c5e5c4d8da12c543d82b03d6089eb77c5",
   "v8/third_party/icu":
     Var("git_url") + "/chromium/deps/icu.git" + "@" + "bbb24c53b4f46025e87a5973c39fa722c8757595",
   "v8/buildtools":
     Var("git_url") + "/chromium/buildtools.git" + "@" + "565d04e8741429fb1b4f26d102f2c6c3b849edeb",
   "v8/testing/gtest":
     Var("git_url") + "/external/googletest.git" + "@" + "9855a87157778d39b95eccfb201a9dc90f6d61c6",
   "v8/testing/gmock":
     Var("git_url") + "/external/googlemock.git" + "@" + "0421b6f358139f02e102c9c332ce19a33faf75be",
   "v8/tools/clang":
-    Var("git_url") + "/chromium/src/tools/clang.git" + "@" + "c9a343c6a8065127989a05fe2a3fc76c26ad8102",
+    Var("git_url") + "/chromium/src/tools/clang.git" + "@" + "c956d7970bf6637cb34f17ff64c375b6591d5940",
 }
 
 deps_os = {
   "android": {
     "v8/third_party/android_tools":
       Var("git_url") + "/android_tools.git" + "@" + "2bb73b7af7da7116aa54c1474121c28a85d28e6b",
   },
   "win": {
     "v8/third_party/cygwin":
       Var("git_url") + "/chromium/deps/cygwin.git" + "@" + "c89e446b273697fadf3a10ff1007a97c0b7de6df",
@@ skipping 76 matching lines @@
     'name': 'clang',
     'pattern': '.',
     'action': ['python', 'v8/tools/clang/scripts/update.py', '--if-needed'],
   },
   {
     # A change to a .gyp, .gypi, or to GYP itself should run the generator.
     "pattern": ".",
     "action": ["python", "v8/build/gyp_v8"],
   },
 ]