clang-format: Don't let -style=Chromium imply c++03 template formatting.

Chromium's now using some c++11 language features, so it's now fine that
clang-format produces vector<vector<int>>.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@218392 91177308-0d34-0410-b5e6-96231b3b80d8