With Style.BreakBeforeBinaryOperators, clang-format breaks incorrectly.
This fixes llvm.org/PR17994.

Before:
  return boost::fusion::at_c<0>(iiii).second == boost::fusion::at_c
                                                <1>(iiii).second;

After:
  return boost::fusion::at_c<0>(iiii).second ==
         boost::fusion::at_c<1>(iiii).second;

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@195552 91177308-0d34-0410-b5e6-96231b3b80d8