* more fixes for segment register usage

git-svn-id: http://svn.freepascal.org/svn/fpc/trunk@24584 3ad0048d-3df7-0310-abae-a5850022a9f2
* more readable register allocation comments

git-svn-id: http://svn.freepascal.org/svn/fpc/trunk@24585 3ad0048d-3df7-0310-abae-a5850022a9f2