Fix macOS toolchains with Xcode new build system.

[dan-zheng]

Xcode's new build system requires the Version entry in Info.plist to have a
particular date-based format.

Resolves tensorflow/swift#350:

2019-12-24 15:47:16.618 XCBBuildService[75398:12495542] /Library/Developer/Toolchains/swift-tensorflow-DEVELOPMENT-2019-12-12-a.xctoolchain: warning: failed to load toolchain: 'Version' parse error: Could not parse version component from: 'swift-tensorflow-DEVELOPMENT-2019-12-12-a'

Swift for TensorFlow macOS toolchain working with Xcode new build system:

[dan-zheng]

This issue also exists in the upstream utils/build-toolchain script. We should submit a patch upstream as well.

On the forums, someone discovered this issue in utils/build-toolchain but didn't submit a fix.

[dan-zheng]

Running CI is not meaningful because utils/build-toolchain-tensorflow is untested.

Verified that newly built macOS toolchains work with Xcode new build system: tensorflow/swift#349

[RahulBhalley]

Does that mean we can build, run, and debug (as shown in Manifesto GIF) in Xcode itself now instead of running the program as swift main.swift?

[dan-zheng]

Does that mean we can build, run, and debug (as shown in Manifesto GIF) in Xcode itself now instead of running the program as swift main.swift?

AutoDiff reverse debugging has actually always been possible (with Xcode's legacy build system) before this patch.

[RahulBhalley]

But I have never been able to run my S4TF program in Xcode although I could build them. And I can only run this with swift main.swift approach in terminal.

I have tried this solution with a fresh new Command Line Project but no success. I still have problem with this new swift-tensorflow-DEVELOPMENT-2019-12-23 toolchain.

[RahulBhalley]

Ok, so this worked for me. Thanks to Daisuke!