spec: Add note about source of ifenslave code

Related: #1938746

iputils.spec

@@ -3,13 +3,14 @@
 Summary: Network monitoring tools including ping
 Name: iputils
 Version: 20210202
-Release: 4%{?dist}
+Release: 5%{?dist}
 # some parts are under the original BSD (ping.c)
 # some are under GPLv2+ (tracepath.c)
 License: BSD and GPLv2+
 URL: https://github.com/iputils/iputils
 
 Source0: https://github.com/iputils/iputils/archive/%{version}/%{name}-%{version}.tar.gz
+# ifenslave.tar.gz was taken from kernel 3.10 source at: https://elixir.bootlin.com/linux/v3.10/source/Documentation/networking/ifenslave.c
 Source1: ifenslave.tar.gz
 Source2: rdisc.service
 Source3: ninfod.service
@@ -134,6 +135,9 @@ install -cp ifenslave.8 ${RPM_BUILD_ROOT}%{_mandir}/man8/
 %attr(644,root,root) %{_mandir}/man8/ninfod.8.gz
 
 %changelog
+* Mon Jun 14 2021 Jan Macku <jamacku@redhat.com> - 20210202-5
+- spec: Add note about source of ifenslave code (rhbz#1938746)
+
 * Wed Jun 09 2021 Jan Macku <jamacku@redhat.com> - 20210202-4
 - ifenslave: fix CWE-170 (rhbz#1938746)