use socket.shutdown where timeout

lualib/http/httpc.lua

@@ -106,7 +106,7 @@ function httpc.request(method, host, url, recvheader, header, content)
 			if not finish then
 				local temp = fd
 				fd = nil
-				socket.close(temp)
+				socket.shutdown(temp)
 			end
 		end)
 	end

lualib/http/sockethelper.lua

@@ -102,4 +102,8 @@ function sockethelper.close(fd)
 	socket.close(fd)
 end
 
+function sockethelper.shutdown(fd)
+	socket.shutdown(fd)
+end
+
 return sockethelper