Do not allow blockfile pruning during reindex.

Also clarify startup message.

src/init.cpp

@@ -1498,10 +1498,10 @@ bool AppInit2(boost::thread_group& threadGroup, CScheduler& scheduler)
     // if pruning, unset the service bit and perform the initial blockstore prune
     // after any wallet rescanning has taken place.
     if (fPruneMode) {
-        uiInterface.InitMessage(_("Pruning blockstore..."));
         LogPrintf("Unsetting NODE_NETWORK on prune mode\n");
         nLocalServices &= ~NODE_NETWORK;
         if (!fReindex) {
+            uiInterface.InitMessage(_("Pruning blockstore..."));
             PruneAndFlush();
         }
     }