[libc++][test] Allow multiple tries in some thread tests

libcxx/test/libcxx/thread/thread.threads/thread.thread.this/sleep_for.pass.cpp

@@ -13,6 +13,8 @@
 // corresponding system libraries.
 // UNSUPPORTED: use_system_cxx_lib && target={{.+}}-apple-macosx10.{{9|10|11}}
 
+// ALLOW_RETRIES: 3
+
 // <thread>
 
 // template <class Rep, class Period>

libcxx/test/libcxx/thread/thread.threads/thread.thread.this/sleep_for.signals.pass.cpp

@@ -16,6 +16,8 @@
 // libraries.
 // XFAIL: use_system_cxx_lib && target={{.+}}-apple-macosx10.{{9|10|11}}
 
+// ALLOW_RETRIES: 3
+
 // <thread>
 
 // template <class Rep, class Period>

libcxx/test/std/thread/futures/futures.unique_future/wait_for.pass.cpp

@@ -9,6 +9,8 @@
 // UNSUPPORTED: libcpp-has-no-threads
 // UNSUPPORTED: c++03
 
+// ALLOW_RETRIES: 3
+
 // <future>
 
 // class future<R>

libcxx/test/std/thread/thread.mutex/thread.mutex.requirements/thread.sharedtimedmutex.requirements/thread.sharedtimedmutex.class/lock.pass.cpp

@@ -12,6 +12,8 @@
 // shared_timed_mutex was introduced in macosx10.12
 // UNSUPPORTED: use_system_cxx_lib && target={{.+}}-apple-macosx10.{{9|10|11}}
 
+// ALLOW_RETRIES: 3
+
 // <shared_mutex>
 
 // class shared_timed_mutex;

libcxx/test/std/thread/thread.mutex/thread.mutex.requirements/thread.sharedtimedmutex.requirements/thread.sharedtimedmutex.class/lock_shared.pass.cpp

@@ -12,6 +12,8 @@
 // shared_timed_mutex was introduced in macosx10.12
 // UNSUPPORTED: use_system_cxx_lib && target={{.+}}-apple-macosx10.{{9|10|11}}
 
+// ALLOW_RETRIES: 3
+
 // <shared_mutex>
 
 // class shared_timed_mutex;