ClangCodeModel: Ignore boolean and pointer literals

... when doing semantic highlighting. The syntax highlighter already
handles these.

Change-Id: I048e033eda5b72d2e6eafaaccdb66040a00afe6a
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: <github-actions-qt-creator@cristianadam.eu>
Reviewed-by: David Schulz <david.schulz@qt.io>

src/plugins/cppeditor/testcases/highlightingtestcase.cpp

@@ -5,3 +5,10 @@ auto func()
         R"notaprefix!(
     barfoobar)" R"(second)" /* comment */ R"(third)";
 }
+
+void keywords()
+{
+    bool b1 = true;
+    bool b2 = false;
+    void *p = nullptr;
+}