+ added is_farpointer(tdef) and is_hugepointer(tdef) helper functions to defutil

git-svn-id: http://svn.freepascal.org/svn/fpc/trunk@24865 3ad0048d-3df7-0310-abae-a5850022a9f2
* when doing a pointer comparison on i8086, don't cast a far pointer to a near one (pchar), but use a far one instead

git-svn-id: http://svn.freepascal.org/svn/fpc/trunk@24866 3ad0048d-3df7-0310-abae-a5850022a9f2
+ medium memory model added to the compiler help messages

git-svn-id: http://svn.freepascal.org/svn/fpc/trunk@24867 3ad0048d-3df7-0310-abae-a5850022a9f2