Attachment: Download

Issue Description:

`generate-xcodeproj` fails to `-I` include from `CXXSetting.headerSearchPath("Realm/ObjectStore/src")`

A build of `swift package generate-xcodeproj` generated project is expected to provide includes base on any '.headerSearchPath(…)' just like `swift build` does.

Addition discussion can be found in the GitHub realm/realm-cocoa issue #6345. (realm/realm-swift#6345).

Steps

1. An example project is provided as an attachment and as the GitHub repository marc-medley/RealmSPMXcode. (https://github.com/marc-medley/RealmSPMXcode).

2. Build the example project with `swift build`. The build should complete with a small number of warning not related to this issue. Observe that the expected includes are present: "-I.../RealmSPMXcode/.build/checkouts/realm-cocoa/Realm/ObjectStore/src". And, later in the log file more instances of "Realm/ObjectStore/src" are present like "-MF '.../RealmSPMXcode/.build/x86_64-apple-macosx/debug/Realm.build/Realm/ObjectStore/src". See attached log-swift_build.txt.

3. Create an Xcode project with `swift package generate-xcodeproj`. Build the generated Xcode project. Observe the absense of "Realm/ObjectStore/src" in the build log. See attached log-generation-xcode-build.txt.

Note that the expressly stated `headerSearchPath(...)` incluse are present in step 2 but not in step 3.