unittests: skip some tests on AL2 due to rdar://163604876

It's blocking the Swift CI job https://ci.swift.org/job/oss-swift-package-amazon-linux-2-aarch64/

Author: kavon

unittests/runtime/Actor.cpp

@@ -318,6 +318,9 @@ TEST(ActorTest, actorSwitch) {
 }
 
 TEST(ActorTest, actorContention) {
+  #ifdef __SKIP_RDAR163604876__
+    GTEST_SKIP() << "Skipping due to rdar://163604876";
+  #endif
   run([] {
     using Context = TupleContext<AsyncTask*, TestActor*>;
     auto actor = createActor();
@@ -387,6 +390,9 @@ TEST(ActorTest, actorContention) {
 }
 
 TEST(ActorTest, actorPriority) {
+  #ifdef __SKIP_RDAR163604876__
+    GTEST_SKIP() << "Skipping due to rdar://163604876";
+  #endif
   run([] {
     auto actor = createActor();
 
@@ -430,6 +436,9 @@ TEST(ActorTest, actorPriority) {
 }
 
 TEST(ActorTest, actorPriority2) {
+  #ifdef __SKIP_RDAR163604876__
+    GTEST_SKIP() << "Skipping due to rdar://163604876";
+  #endif
   run([] {
     auto actor = createActor();
 

unittests/runtime/CMakeLists.txt

@@ -183,4 +183,13 @@ if(("${SWIFT_HOST_VARIANT_SDK}" STREQUAL "${SWIFT_PRIMARY_VARIANT_SDK}") AND
 #
 # to add the preprocessor definition.
 
+
+# A few unit tests with actor scheduling are failing AL2 aarch64 (rdar://163604876)
+if(EXISTS "/etc/os-release")
+    file(READ "/etc/os-release" OS_RELEASE)
+    if(OS_RELEASE MATCHES "Amazon Linux 2" AND CMAKE_SYSTEM_PROCESSOR MATCHES "aarch64|ARM64|arm64")
+        target_compile_definitions(SwiftRuntimeTests PRIVATE __SKIP_RDAR163604876__)
+    endif()
+endif()
+
 endif()