Merge remote-tracking branch 'origin/1.9' into 1.10

src/box/errcode.h

src/box/memtx_engine.c

src/box/txn.c

src/box/txn.h

src/box/vinyl.c

test/app/fiber.result

test/app/fiber.test.lua

test/box/ddl.result

test/box/ddl.test.lua

test/box/misc.result

test/box/transaction.result

test/engine/iterator.result

test/engine/iterator.test.lua