1) We don't need to call FindPose() on every pose as we're freshly adding it,
and a duplicate should never happen in this circumstance (the FindPose() is still there if
Tracker is compiled in debug mode however.
2) Adjust the FSClipboard calls such that the locking is optional. This allows us to lock
once per CreatePoses group rather than once per pose.
Together these changes make for a significant performance improvement when it comes to
populating a large folder.
git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@29198 a95241bf-73f2-0310-859d-f6bbb57e9c96