Automatic merge from submit-queue (batch tested with PRs 38315, 38624, 38572, 38544)

Fix code coverage in build script on OS X.

Fixes #20223

- Fixes code coverage in build script on BSD systems (including OS X).
- Supersedes #38536.

Successfully tested on two platforms:

```
Darwin <hostname> 16.1.0 Darwin Kernel Version 16.1.0: Thu Oct 13 21:26:57 PDT 2016; root:xnu-3789.21.3~60/RELEASE_X86_64 x86_64
```

```
Linux <hostname> 4.4.14-040414-generic #201606241434 SMP Fri Jun 24 18:36:45 UTC 2016 x86_64 x86_64 x86_64 GNU/Linux
```

cc @ixdy @mfanjie @balajismaniam @smarterclayton @soltysh

**Release note**:
```release-note
```