loplugin constantparam, ignore variadic methods

Change-Id: Ieabb020406d5a381dd9cbace3b1e4cc434857d54
diff --git a/compilerplugins/clang/constantparam.cxx b/compilerplugins/clang/constantparam.cxx
index f5a3d53..d748919 100644
--- a/compilerplugins/clang/constantparam.cxx
+++ b/compilerplugins/clang/constantparam.cxx
@@ -97,6 +97,8 @@ void ConstantParam::addToCallSet(const FunctionDecl* functionDecl, int paramInde

    if (!functionDecl->getNameInfo().getLoc().isValid())
        return;
    if (functionDecl->isVariadic())
        return;
    if (ignoreLocation(functionDecl))
        return;
    // ignore stuff that forms part of the stable URE interface