Fix compile errors

Author: szarnyasg

src/main/java/ldbc/snb/datagen/generator/generators/PersonActivityGenerator.java

@@ -103,7 +103,7 @@ private void generateActivity(Person person, ArrayList<Person> block) throws Ass
     }
 
     public void reset() {
-        dynamicActivitySerializer_.reset();
+//        dynamicActivitySerializer_.reset();
     }
 
     private void generateWall(Person person, ArrayList<Person> block) throws IOException {
@@ -194,7 +194,7 @@ public void generateActivityForBlock(int seed, ArrayList<Person> block, Context
         forumId = 0;
         messageId = 0;
         SN.machineId = seed;
-        dynamicActivitySerializer_.reset();
+//        dynamicActivitySerializer_.reset();
         int counter = 0;
         float personGenerationTime = 0.0f;
         for (Person p : block) {

src/main/java/ldbc/snb/datagen/serializer/empty/EmptyDynamicActivitySerializer.java

@@ -103,8 +103,4 @@ protected void serialize(final Like like) {
         //This is left intentionally blank
     }
 
-    @Override
-    public void reset() {
-        //This is left intentionally blank
-    }
 }