LOCAL: clang 3.x or later warns for unused typedefs

clang 3.x issues the same warning. It should treat it the same way.

Change-Id: I878f3bff06c88af55f07ced7daa93a308863b20b

asio/include/asio/detail/handler_type_requirements.hpp

diff --git a/asio/include/asio/detail/handler_type_requirements.hpp b/asio/include/asio/detail/handler_type_requirements.hpp
index 04bab88..2543015 100644
--- a/asio/include/asio/detail/handler_type_requirements.hpp
+++ b/asio/include/asio/detail/handler_type_requirements.hpp
@@ -54,7 +54,7 @@
 #endif // defined(ASIO_ENABLE_HANDLER_TYPE_REQUIREMENTS)
 
 // Newer gcc, clang need special treatment to suppress unused typedef warnings.
-#if defined(__clang__) && (__clang_major__ >= 7)
+#if defined(__clang__) && (__clang_major__ >= 3)
 # define ASIO_UNUSED_TYPEDEF __attribute__((__unused__))
 #elif defined(__GNUC__)
 # if ((__GNUC__ == 4) && (__GNUC_MINOR__ >= 8)) || (__GNUC__ > 4)