SwiftDriver: adjust handling of -resource-dir parameter

When computing the resource directory for the Swift registrar, we need
to add a couple of components that we had missed. Correct the path
computation so that we can find the object file properly. This was
detected while running the test suite with the early swift driver on
Windows where `-resource-dir` is explicitly passed.

Author: compnerd

Sources/SwiftDriver/Jobs/WindowsToolchain+LinkerSupport.swift

@@ -173,7 +173,10 @@ extension WindowsToolchain {
       // finally falling back to the target information.
       let rsrc: VirtualPath
       if let resourceDir = parsedOptions.getLastArgument(.resourceDir) {
-        rsrc = try VirtualPath(path: resourceDir.asSingle)
+        rsrc = try VirtualPath(path: AbsolutePath(validating: resourceDir.asSingle)
+                                        .appending(components: targetTriple.platformName() ?? "",
+                                                   architecture(for: targetTriple))
+                                        .pathString)
       } else if let sdk = parsedOptions.getLastArgument(.sdk)?.asSingle ?? env["SDKROOT"], !sdk.isEmpty {
         rsrc = try VirtualPath(path: AbsolutePath(validating: sdk)
                                         .appending(components: "usr", "lib", "swift",
@@ -182,6 +185,8 @@ extension WindowsToolchain {
                                         .pathString)
       } else {
         rsrc = VirtualPath.lookup(targetInfo.runtimeResourcePath.path)
+                          .appending(components: targetTriple.platformName() ?? "",
+                                     architecture(for: targetTriple))
       }
       commandLine.appendPath(rsrc.appending(component: "swiftrt.obj"))
     }