[Swift Build] Wire up --jobs

Author: owenv

Sources/SwiftBuildSupport/SwiftBuildSystem.swift

@@ -1002,6 +1002,7 @@ public final class SwiftBuildSystem: SPMBuildCore.BuildSystem {
         request.useDryRun = false
         request.hideShellScriptEnvironment = true
         request.showNonLoggedProgress = true
+        request.schedulerLaneWidthOverride = buildParameters.workers
 
         // Override the arena. We need to apply the arena info to both the request-global build
         // parameters as well as the target-specific build parameters, since they may have been