Apply clang-format universally.

* It is tough to contribute to a project that doesn't use a formatter,
* It is extra hard to contribute to a project which has configured the formatter, but ignores it for some files
* Code formatting makes it harder to hide obscure / weird bugs by accident or on purpose,

Let's rip the bandaid off?

Note that PRs currently in flight should be able to be merged relatively easily by applying `clang-format` to their tip prior to merge.

src/libutil/tarfile.cc

@@ -44,7 +44,7 @@ void checkLibArchive(archive * archive, int err, const std::string & reason)
 }
 
 constexpr auto defaultBufferSize = std::size_t{65536};
-}
+} // namespace
 
 void TarArchive::check(int err, const std::string & reason)
 {
@@ -247,4 +247,4 @@ time_t unpackTarfileToSink(TarArchive & archive, ExtendedFileSystemObjectSink &
     return lastModified;
 }
 
-}
+} // namespace nix