Re: [libvirt PATCH 0/1] DO NOT MERGE: RFC: targetted usage of clang-format

While we have a code style, it is not perfectly applied across the code base because its impossible for humans to manage that without using automated tooling. clang-format is the closest we'll get to a code formatter we could use, but still it would reformat quite alot of our code. I discovered that '/* clang-format off */' can be used to stop it from reformatting sections of code. It is not practical to add that comment around all places we don't want touched. I thought we could perhaps use it as a way to limit clang-format to merely do sorting & regrouping of #include statements though. This change illustrates what that would look like for the src/util directory, so we can consider whuether it is worth it. I've included a mark.pl script that I usd to auto-add the magic comment. It gets it wrong sometimes, so needs inspection. If we did decide to use this, we would need the magic comment in every existing source file. Then there is the question about new source files. If a contributor forgets to add the comment, then entire new source file will be processed by clang-format. This might be desirable. If so, we will need to fully expand the .clang-format config file to match ou4r desired style. Right now I only recorded include file rules. Or we could just wrong a dumb script to do #include sorting ourselves and carry on ignoring clang-format. I'm pretty undecided myself.