Small improvements for generate_specializations.

pgenutil.pas, generate_specializations:
  * use splite_generic_name
  * use the genericparas list instead of iterating the complete symlist
pgenutil.pas, split_generic_name:
  * leave the loop instead of providing an internal error if the right part is not a number


git-svn-id: http://svn.freepascal.org/svn/fpc/trunk@25580 3ad0048d-3df7-0310-abae-a5850022a9f2