PWGLF: fix seeding issues

Author: ddobrigk

MC/config/PWGLF/pythia8/generator_pythia8_extraStrangeness.C

@@ -278,5 +278,9 @@ private:
 
  FairGenerator *generator_extraStrangeness()
  {
-   return new GeneratorPythia8ExtraStrangeness();
+  auto generator = new GeneratorPythia8ExtraStrangeness();
+  gRandom->SetSeed(0);
+  generator.readString("Random:setSeed = on");
+  generator.readString("Random:seed =" + std::to_string(gRandom->Integer(900000000 - 2) + 1));
+  return generator;
  }

MC/config/PWGLF/pythia8/generator_pythia8_syntheFlow.C

@@ -99,5 +99,9 @@ private:
 
  FairGenerator *generator_syntheFlow()
  {
-   return new GeneratorPythia8SyntheFlow();
+  auto generator = new GeneratorPythia8SyntheFlow();
+  gRandom->SetSeed(0);
+  generator.readString("Random:setSeed = on");
+  generator.readString("Random:seed =" + std::to_string(gRandom->Integer(900000000 - 2) + 1));
+  return generator;
  }

MC/config/PWGLF/pythia8/generator_pythia8_syntheFlowXi.C

@@ -335,5 +335,9 @@ private:
 
  FairGenerator *generator_syntheFlowXi()
  {
-   return new GeneratorPythia8SyntheFlowXi();
+  auto generator = new GeneratorPythia8SyntheFlowXi();
+  gRandom->SetSeed(0);
+  generator.readString("Random:setSeed = on");
+  generator.readString("Random:seed =" + std::to_string(gRandom->Integer(900000000 - 2) + 1));
+  return generator;
  }