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" + "@" + "fe00999dfaee449d3465a9316778434884da4fa7",  # from svn revision 2010
   "v8/third_party/icu":
     Var("git_url") + "/chromium/deps/icu.git" + "@" + "53ecf0f68b27a004bef5526553b8e5f6c235b80b",
   "v8/buildtools":
     Var("git_url") + "/chromium/buildtools.git" + "@" + "4995faa4a7ad968f1fa1917c26edd5cea295582f",
   "v8/testing/gtest":
     Var("git_url") + "/external/googletest.git" + "@" + "8245545b6dc9c4703e6496d1efd19e975ad2b038",  # from svn revision 700
   "v8/testing/gmock":
     Var("git_url") + "/external/googlemock.git" + "@" + "29763965ab52f24565299976b936d1265cb6a271",  # from svn revision 501
   "v8/tools/clang":
-    Var("git_url") + "/chromium/src/tools/clang.git" + "@" + "3569efa494f668b68bd13835ab4f197f6a51b84a",
+    Var("git_url") + "/chromium/src/tools/clang.git" + "@" + "6538d768c1dd43ad3942574cfc5ba90a8e1e0517",
 }
 
 deps_os = {
   "android": {
     "v8/third_party/android_tools":
       Var("git_url") + "/android_tools.git" + "@" + "4f723e2a5fa5b7b8a198072ac19b92344be2b271",
   },
   "win": {
     "v8/third_party/cygwin":
       Var("git_url") + "/chromium/deps/cygwin.git" + "@" + "c89e446b273697fadf3a10ff1007a97c0b7de6df",
@@ skipping 54 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"],
   },
 ]