[clang-format] Re-align broken comment lines where appropriate.

Summary:
The comment aligner was skipping over newly broken comment lines. This patch fixes that.

source:
```
int ab; // line
int a; // long long
```

format with column limit 15 before:
```
int ab; // line
int a;  // long
       // long
```

format with column limit 15 after:
```
int ab; // line
int a;  // long
        // long
```

Reviewers: djasper

Reviewed By: djasper

Subscribers: cfe-commits, klimek

Differential Revision: https://reviews.llvm.org/D29486

llvm-svn: 293997