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

[Paul Kirth via cfe-commits]

ilovepi 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.


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