Add dllprt0 for x86_64 (i386 version simply includes cprt0.as)

git-svn-id: http://svn.freepascal.org/svn/fpc/trunk@23828 3ad0048d-3df7-0310-abae-a5850022a9f2
 * Also use dllprt0 for openbsd

git-svn-id: http://svn.freepascal.org/svn/fpc/trunk@23829 3ad0048d-3df7-0310-abae-a5850022a9f2