Set a mainnet donation zaddr for z_shieldcoinbase

src/wallet/asyncrpcoperation_shieldcoinbase.cpp

@@ -219,9 +219,13 @@ bool ShieldToAddress::operator()(const libzcash::SaplingPaymentAddress &zaddr) c
     if(donation) {
         //if donation>0, send X% of value to zaddr and Y% of of value to donatezaddr where X+Y=100%
 
-        //TODO: TESTING zaddr only, only use on regtest
-        //TODO: randomly select from a set
-        auto dzaddr         = "zregtestsapling1y30nwg0clsu6gcyrnvht8hdyfk3vwtszlh6kc4z5hv9hmpxzg2g0nx7c60xeecggm9x9gma96t4";
+        auto dzaddr =  "";
+        if(Params().NetworkIDString() == "regtest") {
+            dzaddr = "zregtestsapling1y30nwg0clsu6gcyrnvht8hdyfk3vwtszlh6kc4z5hv9hmpxzg2g0nx7c60xeecggm9x9gma96t4";
+        } else {
+            //TODO: randomly select from a set
+            dzaddr = "zs1uhmry4jjaymhh2x7x53fkahp57u60qr54ydtcd6c2nzu73lgm78a4kml2x7ylm547hu2qqtsnw5";
+        }
         auto donationZaddr = DecodePaymentAddress(dzaddr);
         if (!IsValidPaymentAddress(donationZaddr)) {
             throw JSONRPCError(RPC_INVALID_PARAMETER, string("Invalid donation zaddr, Unknown address format: ") + dzaddr);