if_var.h micro-optimization

[rihad]

Not sure if this is a worthwhile optimization? FreeBSD 7.0

--- /usr/src/sys/net/if_var.h   2007-12-07 09:46:08.000000000 +0400
+++ if_var.h    2008-05-30 18:10:25.000000000 +0500
@@ -282,7 +282,8 @@
         if (m) {                                                \
                 if (((ifq)->ifq_head = (m)->m_nextpkt) == NULL) \
                         (ifq)->ifq_tail = NULL;                 \
-               (m)->m_nextpkt = NULL;                          \
+               else                                            \
+                       (m)->m_nextpkt = NULL;                  \
                 (ifq)->ifq_len--;                               \
         }                                                       \
  } while (0)