Fix the last failing tcnvint test (plus another one) by using comparisons that are not necessarily 32-bit.

m68k/n68kadd.pas, tn68kadd.second_cmpordinal:
  * use the size of the largest operand to select a fiting operand
  * ToDo: check whether a sign/zero extend of the value is necessary


git-svn-id: http://svn.freepascal.org/svn/fpc/trunk@25628 3ad0048d-3df7-0310-abae-a5850022a9f2