Fixed bug CORE-4212 : Dropping FK on GTT crashes server

git-svn-id: svn+ssh://svn.code.sf.net/p/firebird/code/firebird/trunk@58595 65644016-39b1-43b1-bf79-96bc8fe82c15
Fixed bug CORE-4214 : GTT should not reference permanent relation

git-svn-id: svn+ssh://svn.code.sf.net/p/firebird/code/firebird/trunk@58598 65644016-39b1-43b1-bf79-96bc8fe82c15