ClangCodeModel: Fix another false positive

... in output argument highlighting.
If there is not enough information for clang to determine the const-ness
of the argument passing (as it can happen in templates), do not report
an output argument.

Change-Id: I8d0143042f02ac44d8d971398014828cff14697f
Reviewed-by: <github-actions-qt-creator@cristianadam.eu>
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: David Schulz <david.schulz@qt.io>

src/plugins/clangcodemodel/test/clangdtests.cpp

@@ -1327,6 +1327,8 @@ void ClangdTestHighlighting::test_data()
                                                   << QList<int>{C_LOCAL} << 0;
     QTest::newRow("call on inherited member") << 1024 << 9 << 1024 << 12
                                                   << QList<int>{C_FIELD} << 0;
+    QTest::newRow("pass inherited member by value") << 1038 << 21 << 1038 << 26
+                                                    << QList<int>{C_FIELD} << 0;
 }
 
 void ClangdTestHighlighting::test()