qemu all apps crash on OS X 10.6.8

qemu-2.0.0-rc0 (and 1.7.1) crashes with SIGABORT in all apps when configured with --with-coroutine=sigaltstack (which is what configure selects by default) but all  run fine if configured with --with-coroutine=gthread.

Crash is at line 253 (last line of Coroutine *qemu_coroutine_new(void)) in coroutine-sigaltstack.c in 2.0.0-rc0 tarball.

Platform is OS X 10.6.8 (Darwin Kernel Version 10.8.0), compiler gcc 4.2.1

Sorry for the sparse report but I'm short on time today.