Refactor shared_timed_mutex tests.

First I removed all of the uses of _LIBCPP_STD_VER and added LIT UNSUPPORTED tags to prevent the tests from being run in older standard dialects.
Second I increased the time tolerances used in some tests when testing with Thread Sanitizer because thread sanitizer make these tests take longer.


git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@245793 91177308-0d34-0410-b5e6-96231b3b80d8

test/std/thread/thread.mutex/thread.lock/thread.lock.shared/thread.lock.shared.obs/op_bool.pass.cpp

@@ -8,6 +8,7 @@
 //===----------------------------------------------------------------------===//
 //
 // UNSUPPORTED: libcpp-has-no-threads
+// UNSUPPORTED: c++98, c++03, c++11
 
 // <shared_mutex>
 
@@ -18,15 +19,10 @@
 #include <shared_mutex>
 #include <cassert>
 
-#if _LIBCPP_STD_VER > 11
-
 std::shared_timed_mutex m;
 
-#endif  // _LIBCPP_STD_VER > 11
-
 int main()
 {
-#if _LIBCPP_STD_VER > 11
     std::shared_lock<std::shared_timed_mutex> lk0;
     assert(static_cast<bool>(lk0) == false);
     std::shared_lock<std::shared_timed_mutex> lk1(m);
@@ -34,5 +30,4 @@ int main()
     lk1.unlock();
     assert(static_cast<bool>(lk1) == false);
     static_assert(noexcept(static_cast<bool>(lk0)), "explicit operator bool() must be noexcept");
-#endif  // _LIBCPP_STD_VER > 11
 }