Minor: Ignore Emacs' lock file and backup file.

[sarutak]

What is the purpose of the change

This PR proposes to ignore Emacs' lock file like .#filename and backup file like #filename#.
I sometimes read/write code of Avro using Emacs, and Auto-save file like filename~ are cared in .gitignore but lock file and backup file are not.

Verifying this change

Confirmed git status doesn't complain that such files are not tracked.

Documentation

No user-facing changes added.

[sarutak]

As it's very minor issue, I didn't file to JIRA.
If it's necessary, please let me know.

[martin-g]

IMO you should put those in $HOME/.gitignore, i.e. in your global gitignore file.
Otherwise you may have to ask each and every project you clone locally to add the ignores.

[sarutak]

@martin-g
It sounds reasonable. So, I'll close this PR. Thanks!