Fix usage of refcounted types from another unit.

pdecobj.pas:
  * object_dec: add the hidden $refcount field as public not private as searchsym_in_class() always uses the current unit to handle the visibility


git-svn-id: http://svn.freepascal.org/svn/fpc/branches/svenbarth@28961 3ad0048d-3df7-0310-abae-a5850022a9f2