[clang] [lldb] [llvm] [mlir] [NFC][Support] Add llvm::uninitialized_copy (PR #138174)

[Erich Keane via cfe-commits]

https://github.com/erichkeane approved this pull request.

This looks right, but I'd like someone else to go through to make sure it is right everywhere.

Also, the md5 change looks... odd and counts a lot on the internal representation of md5, so I'm not sure about that one, but at least it is right NOW (Since MD5 inherits from std::array).

https://github.com/llvm/llvm-project/pull/138174