Do not call Free if constructor failed

git-svn-id: http://svn.freepascal.org/svn/fpc/trunk@29298 3ad0048d-3df7-0310-abae-a5850022a9f2
Amicommon: Change back WindowPtr in DiskSize/DiskFree

git-svn-id: http://svn.freepascal.org/svn/fpc/trunk@29299 3ad0048d-3df7-0310-abae-a5850022a9f2