[clang-format] Fix end-of-file comments text proto formatting

Summary:
The case of end-of-file comments was formatted badly:
```
key: value
    # end-of-file comment
```
This patch fixes that formatting:
```
key: value
# end-of-file comment
```

Subscribers: cfe-commits

Differential Revision: https://reviews.llvm.org/D48539

llvm-svn: 335449