[string.conversions]

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@105336 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/include/thread b/include/thread
index 16faed9..5fcd2c9 100644
--- a/include/thread
+++ b/include/thread
@@ -265,10 +265,10 @@
 thread&
 thread::operator=(thread&& __t)
 {
-    if (__t_ != nullptr)
+    if (__t_ != 0)
         terminate();
     __t_ = __t.__t_;
-    __t.__t_ = nullptr;
+    __t.__t_ = 0;
     return *this;
 }