The universe constraint manager is more flexible now.
We don't need to start with a huge universe U >= 512.
We can start small, and increase it on demand.
If module mod1 needs it, it can always add
universe U >= 3
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
(optional) Boost (version >= 1.54), we can
build Lean using boost::thread instead of std::thread. When using
Boost, Lean can modify the thread stack size.
2b2aa228e3
