Setup single dependency mode

[cltnschlosser]

Adapted from: swiftlang/swift@2a79331

Fixes validation-test/Driver/batch_mode_size_limit.swift

[DougGregor]

Uh oh. We were thinking of removing this feature entirely from the old Swift driver, and instead having the build systems only ask for a single dependency file.

[cltnschlosser]

Uh oh. We were thinking of removing this feature entirely from the old Swift driver, and instead having the build systems only ask for a single dependency file.

Haha, maybe we just let this one sit then. Or close now if we are sure this feature is going to be removed. I’ve just been going through the lit test failures and picking files that sound interesting.

[DougGregor]

I'm fine with letting it sit until we're sure, thanks

[cltnschlosser]

Should I pull out the driver show lifecycle stuff into a separate PR?

[DougGregor]

Should I pull out the driver show lifecycle stuff into a separate PR?

Yes, please!

[shahmishal]

The Swift project moved the default branch to main and deleted master branch, so GitHub automatically closed the PR. Please re-create pull request with main branch.

More detail about the branch update - https://forums.swift.org/t/updating-branch-names/40412