Fix for Mantis #26749 .

pgenutil.pas, generate_specialization:
  * first check whether we can reuse the current specialization or another specialization and only /then/ retrieve the symtable to specialize to

+ added test


git-svn-id: http://svn.freepascal.org/svn/fpc/trunk@28705 3ad0048d-3df7-0310-abae-a5850022a9f2