s3-vfs_gpfs: Fix bug #9003, posix acl on gpfs

s3-vfs_gpfs: Fix bug #9003, posix acl on gpfs

gpfs2smb_acl can leave errno!=0 around even if it returned a correct
result!=NULL. We can only rely on errno being set if another error
condition (in this case result==NULL) indicates an error. If
result!=NULL, errno is undefined and can be anything. This leads to
SAFE_FREE(result) further down even in the success case.

Signed-off-by: Stefan Metzmacher <metze@samba.org>
Autobuild-User(master): Stefan Metzmacher <metze@samba.org>
Autobuild-Date(master): Fri Jun 22 19:27:39 CEST 2012 on sn-devel-104
(cherry picked from commit e7b58146d8576ae8bf4eaf2ec1063fe7697e05b8)