Fix skipCfg for parameter declaration identifiers

Author: owen-mc

go/ql/lib/semmle/go/controlflow/ControlFlowGraphImpl.qll

@@ -62,7 +62,9 @@ module CfgImpl {
       or
       e = any(Go::StructLit sl).getKey(_)
       or
-      e instanceof Go::Ident and not e instanceof Go::ReferenceExpr
+      e instanceof Go::Ident and
+      not e instanceof Go::ReferenceExpr and
+      not e = any(Go::Parameter p).getDeclaration()
       or
       e instanceof Go::SelectorExpr and not e instanceof Go::ReferenceExpr
       or