* Re-implement ln(x) also for x87-based x86_64 targets (counterpart of r27367,r27518,r27552,r27553 for i386 target).

git-svn-id: http://svn.freepascal.org/svn/fpc/trunk@29131 3ad0048d-3df7-0310-abae-a5850022a9f2