compiler: allow comparative operators to have result other than Boolean. Reasons:
1. It allows to use comparative operators in some unusual cases (issue #25004).
2. Regular type checking does not allow to use other than Boolean types in IF expressions anyway.
3. Delphi compatibility (although Delphi documentation states otherwise).

git-svn-id: http://svn.freepascal.org/svn/fpc/trunk@25494 3ad0048d-3df7-0310-abae-a5850022a9f2