Pass toolchain settings when using XCBuild

[neonichu]

This is a follow-up to #3695, adding various other settings of the toolchain that we weren't yet correctly forwarding when XCBuild is being used.

rdar://82313817

[neonichu]

@swift-ci please smoke test

[neonichu]

@DougGregor how can we test that this isn't regressing #3695? I moved things around a bit to bring them more in line with how the toolchain settings are handled when using SwiftPM's own build system.

[DougGregor]

Only way I know how is to open a PR against the Swift repo and do "@swift-ci please build toolchain macOS" in the same comment as you reference this PR. That'll trigger the cross-repo toolchain build to test this change

[neonichu]

/Users/buildnode/jenkins/workspace/swift-package-manager-with-xcode-self-hosted-PR-osx/branch-main/swiftpm/Tests/XCBuildSupportTests/PIFBuilderTests.swift:466: error: -[XCBuildSupportTests.PIFBuilderTests testExecutableProducts] : XCTAssertTrue failed - settings are left unchecked: ["LIBRARY_SEARCH_PATHS"]

Interesting, I didn't see this failure locally, but it makes sense.

[neonichu]

@swift-ci please smoke test

[neonichu]

From the toolchain PR:

20:33:14 28%: Register execution policy exception for PackagePlugin.o
20:33:14 28%: Link libPackagePlugin.dylib (x86_64)
20:33:14 ld: warning: Could not find or use auto-linked library 'swiftCompatibilityConcurrency'
20:33:15 Undefined symbols for architecture x86_64:
20:33:15   "__swift_FORCE_LOAD_$_swiftCompatibilityConcurrency", referenced from:
20:33:15 
20:33:15       __swift_FORCE_LOAD_$_swiftCompatibilityConcurrency_$_PackagePlugin in PackagePlugin.o
20:33:15 
20:33:15 ld: symbol(s) not found for architecture x86_64

So it looks like dynamic products also need the extra library search path, I think this is also not working correctly in SwiftPM's own build system.

[neonichu]

@swift-ci please smoke test

[neonichu]

Looks like building the toolchain succeeded with the latest version, so this should be good to go.

[neonichu]

Updated the plugin case. Don't think we need to re-run the toolchain build since that shouldn't be reached anyway in practice.

[neonichu]

@swift-ci please smoke test