Change CircularCache internal pos members from uint64_t to int64_t.
Merge pull request #2357 from ulion/change_circularcache_pos_member_from_uint64_to_int64

Change CircularCache internal pos members from uint64_t to int64_t.
FIX: in CDAVDirectory::Exists, using PROPFIND without depth might return 403
Fix build after 87047e93e02375851505e9d6c420dd1225996bdb
Merge pull request #2360 from ace20022/fix_build

Fix build after merge of PR #2269
Merge pull request #2361 from koying/fixdavdirectoryexist

FIX: in CDAVDirectory::Exists, using PROPFIND without depth might return 403