Update IncrementalCompilationTests.swift

Mark the test as throwing and `throw XCTSkip` rather than silently returning as per the review comments.

Author: compnerd

Tests/SwiftDriverTests/IncrementalCompilationTests.swift

@@ -134,10 +134,9 @@ extension IncrementalCompilationTests {
   /// Ensure that autolink output file goes with .o directory, to not prevent incremental omission of
   /// autolink job.
   /// Much of the code below is taking from testLinking(), but uses the output file map code here.
-  func testAutolinkOutputPath() {
+  func testAutolinkOutputPath() throws {
 #if os(Windows)
-    // XCTSkip("Driver.init fatalError")
-    return
+    throw XCTSkip("Driver.init fatalError")
 #else
     var env = ProcessEnv.vars
     env["SWIFT_DRIVER_TESTS_ENABLE_EXEC_PATH_FALLBACK"] = "1"