[clang-format] Fix line parsing for noexcept lambdas

Summary:
> $ echo "int c = [b]() mutable noexcept { return [&b] { return b++; }(); }();" |clang-format

```
int c = [b]() mutable noexcept {
  return [&b] { return b++; }();
}
();
```
with patch:
> $ echo "int c = [b]() mutable noexcept { return [&b] { return b++; }(); }();" |bin/clang-format
```
int c = [b]() mutable noexcept { return [&b] { return b++; }(); }();
```

Contributed by hultman.

Reviewers: benhamilton, jolesiak, klimek, Wizard

Reviewed By: benhamilton

Subscribers: cfe-commits

Differential Revision: https://reviews.llvm.org/D56909

llvm-svn: 352622