Ensure that no garbage for specialization code is written in case of "-al"

assemble.pas, TExternalAssembler.WriteSourceLine:
  * also respect a module change which can happen if the generated assembler code belongs to a specialized generic


git-svn-id: http://svn.freepascal.org/svn/fpc/trunk@23628 3ad0048d-3df7-0310-abae-a5850022a9f2