C++: Work around CPP-331

This change suppresses results from "Declaration hides parameter" where
the ParameterDeclarationEntry does not link up to the right
FunctionDeclarationEntry.

cpp/ql/src/Best Practices/Hiding/DeclarationHidesParameter.ql

@@ -23,6 +23,7 @@ ParameterDeclarationEntry functionParameterNames(Function f, string name) {
     result.getFunctionDeclarationEntry() = fe and
     fe.getFunction() = f and
     fe.getLocation() = f.getDefinitionLocation() and
+    result.getFile() = fe.getFile() and // Work around CPP-331
     strictcount(f.getDefinitionLocation()) = 1 and
     result.getName() = name
   )