Postfix for CORE-4461: do not poison backup file with statistics

git-svn-id: svn+ssh://svn.code.sf.net/p/firebird/code/firebird/trunk@59715 65644016-39b1-43b1-bf79-96bc8fe82c15
Implemented CORE-4462 (Make it possible to restore compressed .nbk files without explicitly decompressing them) for POSIX systems

git-svn-id: svn+ssh://svn.code.sf.net/p/firebird/code/firebird/trunk@59716 65644016-39b1-43b1-bf79-96bc8fe82c15
Fixed CORE-4440: isql crash without connect when execute command "show version"

git-svn-id: svn+ssh://svn.code.sf.net/p/firebird/code/firebird/trunk@59717 65644016-39b1-43b1-bf79-96bc8fe82c15