Cross-buildkernel (i386->amd64) is broken?

Hi there,

I've been trying to cross-build an amd64 kernel on i386 host on recent
-CURRENT for a while, and it fails like this:

  $ cd /usr/src && make buildkernel TARGET=amd64 TARGET_ARCH=amd64
  [...]
  In file included from /usr/src/sys/amd64/amd64/genassym.c:46:
  In file included from /usr/src/sys/sys/buf.h:260:
  In file included from /usr/src/sys/sys/proc.h:62:
  /usr/src/sys/sys/pcpu.h:188:1: error: static_assert failed "compile-time assertion failed"
  CTASSERT((PAGE_SIZE / sizeof(struct pcpu)) * sizeof(struct pcpu) == PAGE_SIZE);

Full log is available here: http://193.124.210.26/xbuild-amd64.log

I remember it used to work before (at least at Jun 28th, when I've build
my last kernel this way).  Is is a well known issue?  How do I remedy it?
Thanks.

./danfe