shared_mutex (shared_lock::operator=): Add missing return statement.

	* include/std/shared_mutex (shared_lock::operator=): Add missing
	return statement.

From-SVN: r200141

libstdc++-v3/ChangeLog

 2013-06-16  Jonathan Wakely  <jwakely.gcc@gmail.com>
 
+	* include/std/shared_mutex (shared_lock::operator=): Add missing
+	return statement.
+
+2013-06-16  Jonathan Wakely  <jwakely.gcc@gmail.com>
+
 	PR libstdc++/57263
 	* include/bits/forward_list.h (_Fwd_list_base): Convert to/from
 	allocator's pointer type.

libstdc++-v3/include/std/shared_mutex

@@ -339,7 +339,10 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 
       shared_lock&
       operator=(shared_lock&& __sl) noexcept
-      { shared_lock(std::move(__sl)).swap(*this); }
+      {
+	shared_lock(std::move(__sl)).swap(*this);
+	return *this;
+      }
 
       void
       lock()