don't sample too small list of eligible introducers

libi2pd/SSU2.cpp

@@ -1240,7 +1240,10 @@ namespace transport
 				eligible.push_back (s.second);
 		}
 
-		std::sample (eligible.begin(), eligible.end(), std::back_inserter(ret), maxNumIntroducers, m_Rng);
+		if (eligible.size () <= (size_t)maxNumIntroducers)
+			return eligible;
+		else	
+			std::sample (eligible.begin(), eligible.end(), std::back_inserter(ret), maxNumIntroducers, m_Rng);
 		return ret;
 	}