plist: Reject insertion of plist nodes that already have a parent

Credit to @LkkkLxy for reporting (#276).

libplist nodes are owned by exactly one container. Inserting the same
plist_t into multiple dicts or arrays corrupts the tree structure and
leads to use-after-free crashes during traversal or plist_free().

Add explicit parent checks to dict and array insertion APIs to reject
nodes that already belong to another container. In debug builds, this
fails loudly via assert() and optional diagnostics; in release builds,
the operation safely no-ops.

Callers that need to reuse values must create a copy using plist_copy()
or explicitly detach the node before reinserting it.

0 files changed, 0 insertions, 0 deletions