[clang-format] [PR42417] clang-format inserts a space after '->' for operator->() overloading

Summary:
https://bugs.llvm.org/show_bug.cgi?id=42417

This revision removes the extra space between the opertor-> and the parens ()

```
class Bug {
    auto operator-> () -> int*;
    auto operator++(int) -> int;
};
```

Reviewers: klimek, owenpan, byoungyoung, mitchell-stellar

Reviewed By: mitchell-stellar

Subscribers: cfe-commits

Tags: #clang-format, #clang

Differential Revision: https://reviews.llvm.org/D68242

llvm-svn: 373746