Fix bug https://bugs.launchpad.net/tarantool/+bug/1163858
Fix bug https://bugs.launchpad.net/tarantool/+bug/1163858

Replication relay was created (forked) after initialization
of slab allocator, and, consequently, had a very large address
space. The memory wasn't used really.

Initialize slab allocator after creation of a replication
relay process.

No test case since we don't have automation to detect that sort
of problems.

condor-the-bird/tarantool,dkorolev/tarantool,vasilenkomike/tarantool,KlonD90/tarantool,guard163/tarantool,vasilenkomike/tarantool,Sannis/tarantool,guard163/tarantool,KlonD90/tarantool,nvoron23/tarantool,dkorolev/tarantool,KlonD90/tarantool,ocelot-inc/tarantool,mejedi/tarantool,nvoron23/tarantool,dkorolev/tarantool,Sannis/tarantool,condor-the-bird/tarantool,rtsisyk/tarantool,vasilenkomike/tarantool,Sannis/tarantool,ocelot-inc/tarantool,nvoron23/tarantool,ocelot-inc/tarantool,mejedi/tarantool,guard163/tarantool,guard163/tarantool,Sannis/tarantool,rtsisyk/tarantool,condor-the-bird/tarantool,vasilenkomike/tarantool,Sannis/tarantool,KlonD90/tarantool,rtsisyk/tarantool,guard163/tarantool,mejedi/tarantool,KlonD90/tarantool,nvoron23/tarantool,condor-the-bird/tarantool,rtsisyk/tarantool,nvoron23/tarantool,dkorolev/tarantool,vasilenkomike/tarantool,nvoron23/tarantool,condor-the-bird/tarantool,mejedi/tarantool,ocelot-inc/tarantool,dkorolev/tarantool