Fix the name uniqueness check for editbones. The function can receive a
"bone to ignore", which would not be properly ignored. If it was found
earlier in `armature->edbo` than another bone with the same name, the
name would incorrectly be marked as unique.
This issue only occurred when a "bone to ignore" was passed to the
uniqueness check. This never actually happens in the current code, but
that's going to change soon.
ce8a032ac2