attempt at msvc-10.0 build fix for test_dhy + small documentation note

include/libtorrent/session.hpp

@@ -953,6 +953,12 @@ namespace libtorrent
 		// this blocking call, the dispatcher can be called and it can pop the
 		// alert independently.
 		// 
+		// .. note::
+		// 	Although these functions are all thread-safe, popping alerts from
+		// 	multiple separate threads may introduce race conditions in that
+		// 	the thread issuing an asynchronous operation may not be the one
+		// 	receiving the alert with the result.
+		// 
 		// In the python binding, ``wait_for_alert`` takes the number of
 		// milliseconds to wait as an integer.
 		// 

test/test_dht.cpp

@@ -762,8 +762,11 @@ int test_main()
 
 	// ==== get / put mutable items ===
 
-	std::pair<const char*, int> itemv;
-	std::pair<char const*, int> empty_salt(NULL, 0);
+	std::pair<char const*, int> itemv;
+	std::pair<char const*, int> empty_salt;
+	empty_salt.first = NULL;
+	empty_salt.second = 0;
+
 	char signature[item_sig_len];
 	char buffer[1200];
 	int seq = 4;