This started failing sometime after 2011-11-01 at 20:50:04 UTC:
if_gre.o: In function `gre_bufq_purge':
if_gre.c:(.text+0x1a1): undefined reference to `pcq_get'
if_gre.o: In function `gre_clone_destroy':
if_gre.c:(.text+0x3d3): undefined reference to `pcq_destroy'
if_gre.o: In function `gre_clone_create':
if_gre.c:(.text+0x682): undefined reference to `pcq_create'
if_gre.o: In function `gre_output':
if_gre.c:(.text+0xa3e): undefined reference to `pcq_put'
if_gre.o: In function `greintr':
if_gre.c:(.text+0xb58): undefined reference to `pcq_get'