Update gitignore with a few test dirs/files.

I found these existed and were not ignored after a full test run.
Merge branch 'master' of github.com:chapel-lang/chapel into update-gitignore
Merge pull request #213 from thomasvandoren/update-gitignore

Update gitignore with a few test dirs/files.

I found these existed and were not ignored after a full test run.