Make orphan parent fetching ask for witnesses.

In 0.13 orphan transactions began being treated as implicit
 INVs for their parents.  But the resulting getdata were
 not getting the witness flag.

This fixes issue #9182 reported by chjj and roasbeef on IRC.

src/main.cpp

@@ -5686,8 +5686,9 @@ bool static ProcessMessage(CNode* pfrom, string strCommand, CDataStream& vRecv,
                 }
             }
             if (!fRejectedParents) {
+                uint32_t nFetchFlags = GetFetchFlags(pfrom, chainActive.Tip(), chainparams.GetConsensus());
                 BOOST_FOREACH(const CTxIn& txin, tx.vin) {
-                    CInv _inv(MSG_TX, txin.prevout.hash);
+                    CInv _inv(MSG_TX | nFetchFlags, txin.prevout.hash);
                     pfrom->AddInventoryKnown(_inv);
                     if (!AlreadyHave(_inv)) pfrom->AskFor(_inv);
                 }