Fix duplicated "Done" output

Summary: `PhutilLibraryMapBuilder` outputs "Done" twice, once implicitly from `PhutilConsoleProgressBar` and another explicitly.

Test Plan:
**Before**
```
> arc liberate src
Finding source files...
Found 350 files.
Loading symbol cache...
Found 0 files in cache.
Analyzing 350 files with 8 subprocesses...
Done.

Done.
Building library map...
Writing map...
```

**After**
```
> arc liberate src
Finding source files...
Found 350 files.
Loading symbol cache...
Found 349 files in cache.
Analyzing 1 files with 8 subprocesses...
Done.
Building library map...
Writing map...
```

Reviewers: #blessed_reviewers, epriestley

Reviewed By: #blessed_reviewers, epriestley

Subscribers: epriestley, Korvin

Differential Revision: https://secure.phabricator.com/D9870