Added workaround for the problem that IDEA doesn't allow keywords in cls annotations.

idea/testData/inspections/unusedSymbol/function/inspectionData/expected.xml

@@ -51,4 +51,13 @@
     <problem_class severity="WARNING" attribute_key="NOT_USED_ELEMENT_ATTRIBUTES">Unused Symbol</problem_class>
     <description>Function 'unused' is never used</description>
   </problem>
+
+  <problem>
+    <file>withNativeAnnotation.kt</file>
+    <line>3</line>
+    <module>light_idea_test_case</module>
+    <entry_point TYPE="file" FQNAME="temp:///src/withNativeAnnotation.kt" />
+    <problem_class severity="WARNING" attribute_key="NOT_USED_ELEMENT_ATTRIBUTES">Unused Symbol</problem_class>
+    <description>Function 'withNativeAnnotation' is never used</description>
+  </problem>
 </problems>

idea/testData/inspections/unusedSymbol/function/withNativeAnnotation.kt

@@ -0,0 +1,5 @@
+annotation class native
+
+native fun withNativeAnnotation() {
+
+}