compilerplugins: fix -Werror,-Wunused-parameter

When building the plugins with NDEBUG defined.

Change-Id: If84a920d9e042bf8f45d8e3dd5a5cef3b2baba0b
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/95788
Reviewed-by: Stephan Bergmann <sbergman@redhat.com>
Tested-by: Jenkins
diff --git a/compilerplugins/clang/elidestringvar.cxx b/compilerplugins/clang/elidestringvar.cxx
index 79aa75b..d0336fd 100644
--- a/compilerplugins/clang/elidestringvar.cxx
+++ b/compilerplugins/clang/elidestringvar.cxx
@@ -316,6 +316,7 @@ public:
    {
        assert(!innermostLoop_.empty());
        assert(innermostLoop_.top() == stmt);
        (void)stmt;
        innermostLoop_.pop();
        return true;
    }
@@ -341,6 +342,7 @@ public:
    {
        assert(!innermostLoop_.empty());
        assert(innermostLoop_.top() == stmt);
        (void)stmt;
        innermostLoop_.pop();
        return true;
    }
@@ -366,6 +368,7 @@ public:
    {
        assert(!innermostLoop_.empty());
        assert(innermostLoop_.top() == stmt);
        (void)stmt;
        innermostLoop_.pop();
        return true;
    }
@@ -391,6 +394,7 @@ public:
    {
        assert(!innermostLoop_.empty());
        assert(innermostLoop_.top() == stmt);
        (void)stmt;
        innermostLoop_.pop();
        return true;
    }