SwiftPM libraries are failing to build with the swiftbuild build system with this error when building on Windows x86.

Steps to reproduce:

• Clone the latest SwiftPM on the main branch
• Create a simple library package using the init function:

emptydir=$(mktemp -d)
(cd "$emptydir"; swift package init --type=library)

• Build the project with the swiftbuild build system

swift run swift-build --package-path="$emptydir" --build-system=swiftbuild

Expected Result:
The package should build without error on Windows x86

Actual Result:
The package fails to build with the linker error: "lld-link: error: subsystem must be defined"