Dataflow: Add dummy DataFlowSecondLevelScope implementations.

These could be an empty type, but Unit was available and it probably
doesn't matter.

cpp/ql/lib/semmle/code/cpp/dataflow/internal/DataFlowPrivate.qll

@@ -290,6 +290,8 @@ predicate knownSourceModel(Node source, string model) { none() }
 
 predicate knownSinkModel(Node sink, string model) { none() }
 
+class DataFlowSecondLevelScope = Unit;
+
 /**
  * Holds if flow is allowed to pass from parameter `p` and back to itself as a
  * side-effect, resulting in a summary from `p` to itself.

csharp/ql/lib/semmle/code/csharp/dataflow/internal/DataFlowPrivate.qll

@@ -2882,6 +2882,8 @@ predicate knownSourceModel(Node source, string model) { sourceNode(source, _, mo
 
 predicate knownSinkModel(Node sink, string model) { sinkNode(sink, _, model) }
 
+class DataFlowSecondLevelScope = Unit;
+
 /**
  * Holds if flow is allowed to pass from parameter `p` and back to itself as a
  * side-effect, resulting in a summary from `p` to itself.

go/ql/lib/semmle/go/dataflow/internal/DataFlowPrivate.qll

@@ -415,6 +415,8 @@ predicate knownSourceModel(Node source, string model) { sourceNode(source, _, mo
 
 predicate knownSinkModel(Node sink, string model) { sinkNode(sink, _, model) }
 
+class DataFlowSecondLevelScope = Unit;
+
 /**
  * Holds if flow is allowed to pass from parameter `p` and back to itself as a
  * side-effect, resulting in a summary from `p` to itself.

java/ql/lib/semmle/code/java/dataflow/internal/DataFlowPrivate.qll

@@ -581,6 +581,8 @@ predicate knownSourceModel(Node source, string model) { sourceNode(source, _, mo
 
 predicate knownSinkModel(Node sink, string model) { sinkNode(sink, _, model) }
 
+class DataFlowSecondLevelScope = Unit;
+
 /**
  * Holds if flow is allowed to pass from parameter `p` and back to itself as a
  * side-effect, resulting in a summary from `p` to itself.

python/ql/lib/semmle/python/dataflow/new/internal/DataFlowPrivate.qll

@@ -1087,6 +1087,8 @@ predicate knownSinkModel(Node sink, string model) {
   sink = ModelOutput::getASinkNode(_, model).asSink()
 }
 
+class DataFlowSecondLevelScope = Unit;
+
 /**
  * Holds if flow is allowed to pass from parameter `p` and back to itself as a
  * side-effect, resulting in a summary from `p` to itself.

ruby/ql/lib/codeql/ruby/dataflow/internal/DataFlowPrivate.qll

@@ -2254,6 +2254,8 @@ predicate knownSinkModel(Node sink, string model) {
   sink = ModelOutput::getASinkNode(_, model).asSink()
 }
 
+class DataFlowSecondLevelScope = Unit;
+
 /**
  * Holds if flow is allowed to pass from parameter `p` and back to itself as a
  * side-effect, resulting in a summary from `p` to itself.

swift/ql/lib/codeql/swift/dataflow/internal/DataFlowPrivate.qll

@@ -1404,6 +1404,8 @@ predicate knownSourceModel(Node source, string model) { sourceNode(source, _, mo
 
 predicate knownSinkModel(Node sink, string model) { sinkNode(sink, _, model) }
 
+class DataFlowSecondLevelScope = Unit;
+
 /**
  * Holds if flow is allowed to pass from parameter `p` and back to itself as a
  * side-effect, resulting in a summary from `p` to itself.