Ignore a harmless warning from /usr/include/sys/vnode.h.

scripts/xenofarm.sh

@@ -271,6 +271,7 @@ then
     | grep -v 'aux-item-def-scan\.c:.*: warning: .* defined but not used' \
     | grep -v 'getopt.h:.*: warning: function declaration isn.t a prototype' \
     | grep -v '/usr/include/bits/socket.h:.*: warning: cast increases required alignment of target type' \
+    | grep -v '/usr/include/sys/vnode.h:.*: warning: declaration of .free. shadows global declaration' \
     | grep -v '".*1506-112 .W. Duplicate type qualifier "volatile" ignored.' \
     | grep -v 'sigflags.h:3[06]: warning: duplicate .volatile.' \
     | grep -v 'sigflags.h:3[06]: warning: duplicate .volatile.' \