now works with -fno-exceptions and -fno-rtti

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@110828 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/src/thread.cpp b/src/thread.cpp
index f2db6d5..de53f78 100644
--- a/src/thread.cpp
+++ b/src/thread.cpp
@@ -24,8 +24,10 @@
 thread::join()
 {
     int ec = pthread_join(__t_, 0);
+#ifndef _LIBCPP_NO_EXCEPTIONS
     if (ec)
         throw system_error(error_code(ec, system_category()), "thread::join failed");
+#endif
     __t_ = 0;
 }
 
@@ -39,8 +41,10 @@
         if (ec == 0)
             __t_ = 0;
     }
+#ifndef _LIBCPP_NO_EXCEPTIONS
     if (ec)
         throw system_error(error_code(ec, system_category()), "thread::detach failed");
+#endif
 }
 
 unsigned