Load RTTI symbols indirectly for targets that support packages.

nutils.pas: 
  + add a new function load_typeinfo_pointer_node which generates a node that results in a pointer node of the corresponding RTTI data; this data is loaded indirectly if the target supports packages, otherwise it's loaded directly
nld.pas:
  - remove trttidatatype (moved to symconst.pas)
  + extend trttinode by the possiblity to specify whether the RTTI symbols should be loaded directly or indirectly
  * the resultdef of a trttinode is ^Pointer if the symbols are loaded indirectly
symconst.pas:
  + add trttidatatype (from nld.pas)
* change all caddrnode.create_internal(crttinode.create(a,b,c)) to load_typeinfo_pointer_node(a,b.c)

git-svn-id: http://svn.freepascal.org/svn/fpc/branches/svenbarth@28338 3ad0048d-3df7-0310-abae-a5850022a9f2