M68k: Correctly handle the case of assigning a Boolean expression to a 64-bit Boolean. Fixes tw20889.

* m68k/n68kcnv.pas, tm68ktypeconvnode.second_int_to_bool:
    Take an inspiration from the x86 code generator and correctly handle assignment of values with a size < 8 to 64-bit Booleans


git-svn-id: http://svn.freepascal.org/svn/fpc/trunk@26847 3ad0048d-3df7-0310-abae-a5850022a9f2
Clean up dead code.

m68k/n68kcnv.pas:
  - pass_generate_code is used from the parent class
  - ungetcpuregister is not needed here



git-svn-id: http://svn.freepascal.org/svn/fpc/trunk@26848 3ad0048d-3df7-0310-abae-a5850022a9f2