Restart failure if slab_alloc_arena limit was reached before shutdown

[Kostja Osipov]

If slab_alloc_arena limit was reached while the server was running, then it is shut down, it fails to restart.

[Kostja Osipov (kostja)]

1314941241.672 17240 1/sched _ I> done `/var/tarantool/xlog//00000000000050900000.xlog' confirmed_lsn:50999999
1314941241.672 17240 1/sched _ I> recover from `/var/tarantool/xlog//00000000000051000000.xlog'
1314941241.967 17240 1/sched _ exception.m:78 E> LoggedError at /home/kostja/work/tarantool-newlua/mod/box/tuple.m:45, Failed to allocate 1077 bytes in slab allocator for tuple
1314941241.976 17240 1/sched _ log_io.m:879 E> can't apply row
1314941241.977 17240 1/sched _ log_io.m:983 E> failure reading from /var/tarantool/xlog//00000000000051000000.xlog
1314941241.977 17240 1/sched _ log_io.m:1008 E> not all WALs have been successfully read
1314941241.977 17240 1/sched _ F> recover failed

[Kostja Osipov (kostja)]

Dmitry, this bug must be fixed before we move to the new rollback scheme.