- Add OpenMP to macOS build
- Use as many cores as possible in CI
- Update travis osx image to xcode12.2
- Ignore .vscode folder
- In `.travis/sign-macos.sh`, only create keychain when `CI` variable is present
- Only run macOS deploy stage when a tag is pushed
Travis OS X builders randomly break in ways that aren't reproducible
outside of their VMs, have no Google hits, and are very aggravating;
the two common ones are:
* hdiutil: create failed - Resource busy
* make[2]: write error
This commit drags SNR back into a tolerable range with a gross hack.