file-ids: Fix subnode linkage
file-ids: Fix subnode linkage

The subtree node should be linked with common rbtree procedure. Otherwise
the very first subtree insertion results in an infinite loop in the rb
linking and balancing code.

Plus, mark the root as static and add the subroot node initialization check.

Signed-off-by: Pavel Emelyanov <c9a32589e048e044184536f7ac71ef92fe82df3e@parallels.com>

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