box.slab.stats(): return a correct tuple, not a multi-return
box.slab.stats(): return a correct tuple, not a multi-return

Make box.slab.stats() output CALL compatible.

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