[clang-tools-extra] [clang-doc] Move Info types into arenas (PR #190054)

[via cfe-commits]

dyung wrote:

> > > https://lab.llvm.org/buildbot/#/builders/164/builds/20521 the msan bot seems good now, but darwin still seems unhappy https://lab.llvm.org/buildbot/#/builders/23/builds/19172. I have one more PR I think could solve this, and if not, I'll have to revert the stack.
> > 
> > 
> > Which PR is this? I can take the bot offline and give it a try. Alternatively, is there anything I can easily do that might help to debug the issue?
> 
> The pr is in #191644
> 
> I have a revert up also in #191668, which is sad since it was quite the undertaking to get that part of the stack landed.
> 
> As far as debugging ... IDK. I can't repro on an M4 macbook, so this seems either specific to that builder or to x86 darwin. Its frustrating since the msan bot is green now, so I'm not too sure what I can do other than back it all out.
> 
> Likely there is something subtle going on with the memory management and I'm missing it someplace.

I'll give your change a try and see what happens. FWIW, the failure also doesn't seem to happen on my AArch64 MacOS builder, so it does seem x86 specific.

https://github.com/llvm/llvm-project/pull/190054