CLEANUP: ebtree: remove 4-year old harmless typo in duplicates insertion code

(from ebtree 6.0.7)

This typo has been there since we introduced duplicates. A "struct eb_troot *"
which apparently the compiler doesn't complain about while it is never declared
anywhere. Amazing...

(cherry picked from commit 2879648db5d32cf009ae571cb0e8e1df75152281)
1 file changed