Revamp indentation behavior for complex binary expressions.

The idea is to indent according to operator precedence and pretty much
identical to how stuff would be indented with parenthesis.

Before:
bool value = aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa +
             aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa +
             aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa ==
             aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa *
             bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb +
             bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb &&
             aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa *
             aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa >
             ccccccccccccccccccccccccccccccccccccccccc;

After:
  bool value = aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa +
                       aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa +
                       aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa ==
                   aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa *
                           bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb +
                       bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb &&
               aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa *
                       aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa >
                   ccccccccccccccccccccccccccccccccccccccccc;

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@179049 91177308-0d34-0410-b5e6-96231b3b80d8