Fixed CORE-4460: Expressions containing some built-in functions may be badly optimized.

git-svn-id: svn+ssh://svn.code.sf.net/p/firebird/code/firebird/branches/B2_5_Release@59686 65644016-39b1-43b1-bf79-96bc8fe82c15
Patch by Nickolay Samofatov: avoid an AST overhead for heavily-loaded systems with many requests. This is committed into v2.5 only, so far I doubt v3 needs that.

git-svn-id: svn+ssh://svn.code.sf.net/p/firebird/code/firebird/branches/B2_5_Release@59689 65644016-39b1-43b1-bf79-96bc8fe82c15
nightly update

git-svn-id: svn+ssh://svn.code.sf.net/p/firebird/code/firebird/branches/B2_5_Release@59693 65644016-39b1-43b1-bf79-96bc8fe82c15