Fix bool expression special case.

Clang-format now correctly formats:
  some_type<a * b> v;
  template <bool a, bool b> typename enabled_if<a && b>::type f() {}

git-svn-id: http://llvm.org/svn/llvm-project/cfe/trunk@204913 91177308-0d34-0410-b5e6-96231b3b80d8