rtsock: redundant NULL pointer check

[Tobias Heider]

It seems that there is no way 'rtm' could actually be NULL here, which
means we can get rid of the check.

ok?

Index: net/rtsock.c
===================================================================
RCS file: /mount/openbsd/cvs/src/sys/net/rtsock.c,v
retrieving revision 1.297
diff -u -p -r1.297 rtsock.c
--- net/rtsock.c        24 Nov 2019 07:56:03 -0000      1.297
+++ net/rtsock.c        23 Mar 2020 21:15:51 -0000
@@ -858,14 +858,12 @@ fail:
                        return (error);
                }
        }
-       if (rtm) {
-               if (m_copyback(m, 0, len, rtm, M_NOWAIT)) {
-                       m_freem(m);
-                       m = NULL;
-               } else if (m->m_pkthdr.len > len)
-                       m_adj(m, len - m->m_pkthdr.len);
-               free(rtm, M_RTABLE, len);
-       }
+       if (m_copyback(m, 0, len, rtm, M_NOWAIT)) {
+               m_freem(m);
+               m = NULL;
+       } else if (m->m_pkthdr.len > len)
+               m_adj(m, len - m->m_pkthdr.len);
+       free(rtm, M_RTABLE, len);
        if (m)
                route_input(m, so, info.rti_info[RTAX_DST] ?
                    info.rti_info[RTAX_DST]->sa_family : AF_UNSPEC);