boot CPU wait until all other CPUs are ready to wait. This solves a
theoretical problem in main(): The boot CPU could run fully through the early
initialization and reset sCpuRendezvous2 before the other CPUs left
smp_cpu_rendezvous(). It's very unlikely on real hardware that the non-boot
CPUs are so much slower, but it might be a concern in emulation.
git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@36558 a95241bf-73f2-0310-859d-f6bbb57e9c96