Teach clang-format to understand static_asserts better.

Before:
  template <bool B, bool C>
  class A {
    static_assert(B &&C, "Something is wrong");
  };

After:
  template <bool B, bool C>
  class A {
    static_assert(B && C, "Something is wrong");
  };

(Note the spacing around '&&'). Also change the identifier table to always
understand all C++11 keywords (which seems like the right thing to do).

llvm-svn: 187589