* virtual method pointers in the objpas.TVmt record declared as codepointer; the vmtXXX constants also fixed

git-svn-id: http://svn.freepascal.org/svn/fpc/trunk@25192 3ad0048d-3df7-0310-abae-a5850022a9f2
* terminate the list of virtual method pointers in the vmt with Tai_const.Create_nil_codeptr

git-svn-id: http://svn.freepascal.org/svn/fpc/trunk@25193 3ad0048d-3df7-0310-abae-a5850022a9f2
* use Tai_const.Create_nil_dataptr for creating the nil pointers located before the method table in the class vmt

git-svn-id: http://svn.freepascal.org/svn/fpc/trunk@25194 3ad0048d-3df7-0310-abae-a5850022a9f2