[test] mark multi-thread based tests as UNSUPPORTED in single-thread

Some of test cases assumes that the runtime is built for multi-threaded
platform.

Author: kateinoigakukun

test/Concurrency/Runtime/cancellation_handler.swift

@@ -5,6 +5,7 @@
 // rdar://76038845
 // REQUIRES: concurrency_runtime
 // UNSUPPORTED: back_deployment_runtime
+// UNSUPPORTED: single_threaded_runtime
 
 // for sleep
 #if canImport(Darwin)

test/Concurrency/Runtime/data_race_detection.swift

@@ -8,6 +8,7 @@
 // rdar://76038845
 // REQUIRES: concurrency_runtime
 // UNSUPPORTED: back_deployment_runtime
+// UNSUPPORTED: single_threaded_runtime
 
 import _Concurrency
 import Dispatch
@@ -58,14 +59,14 @@ actor MyActor {
 struct Runner {
   static func main() async {
     print("Launching a main-actor task")
-    // CHECK: warning: data race detected: @MainActor function at main/data_race_detection.swift:22 was not called on the main thread
+    // CHECK: warning: data race detected: @MainActor function at main/data_race_detection.swift:23 was not called on the main thread
     launchFromMainThread()
     sleep(1)
 
     let actor = MyActor()
     let actorFn = await actor.getTaskOnMyActor()
     print("Launching an actor-instance task")
-    // CHECK: warning: data race detected: actor-isolated function at main/data_race_detection.swift:51 was not called on the same actor
+    // CHECK: warning: data race detected: actor-isolated function at main/data_race_detection.swift:52 was not called on the same actor
     launchTask(actorFn)
 
     sleep(1)

test/Concurrency/Runtime/mainactor.swift

@@ -7,6 +7,7 @@
 // rdar://76038845
 // REQUIRES: concurrency_runtime
 // UNSUPPORTED: back_deployment_runtime
+// UNSUPPORTED: single_threaded_runtime
 
 import Dispatch
 

test/Interpreter/enforce_exclusive_access.swift

@@ -4,6 +4,7 @@
 // RUN: %target-codesign %t/a.out
 // RUN: %target-run %t/a.out
 // REQUIRES: executable_test
+// UNSUPPORTED: single_threaded_runtime
 
 // Tests for traps at run time when enforcing exclusive access.
 

validation-test/Runtime/ConcurrentMetadata.swift

@@ -1,5 +1,6 @@
 // RUN: %target-run-simple-swift
 // REQUIRES: executable_test
+// UNSUPPORTED: single_threaded_runtime
 
 // Exercise the metadata cache from multiple threads to shake out any
 // concurrency bugs.