Amiga, AROS, MorphOS: Sysutils, GetDirs must also cut at DriveSeparator

git-svn-id: http://svn.freepascal.org/svn/fpc/trunk@29294 3ad0048d-3df7-0310-abae-a5850022a9f2
* managed types cause a different warning/hint when they are 
  used uninitialized, so users can turn off these messages if they want, resolves #24601 and #26403

git-svn-id: http://svn.freepascal.org/svn/fpc/trunk@29295 3ad0048d-3df7-0310-abae-a5850022a9f2