copy back msg_flags after recvmsg() (we don't really use it yet though)

git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@20564 a95241bf-73f2-0310-859d-f6bbb57e9c96

src/add-ons/kernel/drivers/network/stack/kernel_stack.cpp

@@ -454,6 +454,10 @@ net_stack_control(void *_cookie, uint32 op, void *data, size_t length)
 						return B_BAD_ADDRESS;
 				}
 
+				if (user_memcpy(&args.header->msg_flags, &header.msg_flags,
+								sizeof(int)) < B_OK)
+					return B_BAD_ADDRESS;
+
 				return bytesRead;
 			}