[clang-tidy] Fix [File|Config]OptionsProvider::getOptions

[carlosgalvezp]

#121323 changed the way the absolute path is computed.
This led to HeaderFilterRegex not picked up from the .clang-tidy file sitting at the current working directory. This has partially been fixed by #133582, but nevertheless this should be fixed here as well.

Before the PR:

Getting options for file ''
AbsolutePath: /path/to/root/

After the PR:

Getting options for file ''
AbsolutePath: /path/to/root

I.e. there is a missing trailing slash. This makes the addRawFileOptions no longer work, because it does this:

  StringRef RootPath = llvm::sys::path::parent_path(AbsolutePath);

Since the AbsolutePath no longer has a slash, instead of picking /path/to/root as RootPath, it picks /path/to, and there is no .clang-tidy file there.

[carlosgalvezp]

FYI @HerrCai0907

[llvmbot]

@llvm/issue-subscribers-clang-tidy

Author: Carlos Galvez (carlosgalvezp)

https://github.com//pull/121323 changed the way the absolute path is computed. This led to `HeaderFilterRegex` not picked up from the `.clang-tidy` file sitting at the current working directory. This has partially been fixed by https://github.com//pull/133582, but nevertheless this should be fixed here as well.

Before the PR:

Getting options for file ''
AbsolutePath: /path/to/root/

After the PR:

Getting options for file ''
AbsolutePath: /path/to/root

I.e. there is a missing trailing slash. This makes the addRawFileOptions no longer work, because it does this:

  StringRef RootPath = llvm::sys::path::parent_path(AbsolutePath);

Since the AbsolutePath no longer has a slash, instead of picking /path/to/root as RootPath, it picks /path/to, and there is no .clang-tidy file there.