m68k/n68kmat.pas, tm68kshlshrnode.first_shlshr64bitint:
  use RTL helper functions (through the inherited method) if we're not shifting by a constant

This fixes test/cg/tshlshr


git-svn-id: http://svn.freepascal.org/svn/fpc/trunk@23378 3ad0048d-3df7-0310-abae-a5850022a9f2