Add the offset to the reference count field relative to Self to the VMT (which works better than adding it to the RTTI).

rtl/inc/objpash.inc, TVmt:
  + add a SizeInt field "vRefCountOfs" after "vMsgStrPtr"
compiler/ncgvmt.pas, TVMTWriter:
  * writevmt: use "refcount_field" of the class instance to write the offset to the reference count field to the VMT or 0 if the class isn't reference counted
compiler/symdef.pas, tobjectdef:
  * vmtmethodoffset: adjust the offset by the new SizeInt field


git-svn-id: http://svn.freepascal.org/svn/fpc/branches/svenbarth@28809 3ad0048d-3df7-0310-abae-a5850022a9f2