Add flag to output build logs with build-osx.sh

[kzantow]

When building in CI, logs written to a file are lost when the VM terminates; it is much better to just output to terminal so results can be viewed. It would be fine to add a flag to make this behavior non-default.

Thoughts? Esp. @baconpaul

[baconpaul]

Easy enough to do. Also easy to do with an environment variable. Which do you prefer? Perhaps if you set a uniform ci build env var we can use that elsewhere too?

[kzantow]

I don't really have a preference, though I guess an environment variable would be the most consistent if there are scripts all over using across platforms. I'd like to see what the CMake stuff looks like #128 .

[baconpaul]

I just tossed in a PR which adds a --verbose flag. Check it out and if it works I'll merge it.

[baconpaul]

Thanks for testing the PR. Closing this issue.