TChain::GetEntries apply FriendLockStatus.

Avoid calling LoadTree when it will be a no-op and especially don't undo work we wont be able to
redo

Author: pcanal

tree/tree/src/TChain.cxx

@@ -985,6 +985,10 @@ Long64_t TChain::GetEntries() const
       return fProofChain->GetEntries();
    }
    if (fEntries == TTree::kMaxEntries) {
+      // If the following is true, we are within a recursion about friend,
+      // and `LoadTree` will be no-op.
+      if (kLoadTree & fFriendLockStatus)
+         return fEntries;
       const auto readEntry = fReadEntry;
       auto *thisChain = const_cast<TChain *>(this);
       thisChain->LoadTree(TTree::kMaxEntries - 1);