Small tweak to one check in error handling to the dyld compact export

Small tweak to one check in error handling to the dyld compact export
entries in libObject (done in r308690).  In the case when the last node
has no children setting State.Current = Children + 1; where that would be past
Trie.end() is actually ok since the pointer is not used with zero children.

rdar://33490512

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@308924 91177308-0d34-0410-b5e6-96231b3b80d8