Swift: Rename Negative Summary Model to Neutral Model.

Author: michaelnebel

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

@@ -71,11 +71,11 @@ predicate summaryElement(
 }
 
 /**
- * Holds if a negative flow summary exists for `c`, which means that there is no
- * flow through `c`. The flag `generated` states whether the summary is autogenerated.
- * Note. Negative flow summaries has not been implemented for swift.
+ * Holds if a neutral model exists for `c`, which means that there is no
+ * flow through `c`. The flag `generated` states whether the neutral model is autogenerated.
+ * Note. Neutral models have not been implemented for swift.
  */
-predicate negativeSummaryElement(AbstractFunctionDecl c, boolean generated) { none() }
+predicate neutralElement(AbstractFunctionDecl c, boolean generated) { none() }
 
 /**
  * Holds if an external source specification exists for `e` with output specification