Follow up #429 Replication relay crash with background=true

Duplicate log_fd to STDOUT_FILENO on say_logrotate()

See also 0a1780cbb114f26e3d6b2dda500e48a3bb1eb469
sophia: update to the latest changes, implement index mem_size
Merge branch 'master' of github.com:mailru/tarantool
Merge remote-tracking branch 'origin/fix-logrotate-in-background'
Merge branch 'master' of github.com:tarantool/tarantool
Fix broken tree (sp_error() undeclared).
gh-537: segfault on box.cfg{}

Extract the non-failing parts of the original patch by Roman.
Make an attempt at finding why coeio_custom is crashing when
replication_source is changed quickly - no success yet.
Snapsot_daemon doesn't start its fiber if snapshot_period=0. closes #546
Merge branch 'master' of https://github.com/tarantool/tarantool