[JVM_IR] Fix inlining of callable references to extension methods.

Check directly that the referenced function is an extension
function instead of relying on the annotation on the type.

^ KT-47988 Fixed.

compiler/tests-gen/org/jetbrains/kotlin/codegen/LightAnalysisModeTestGenerated.java

@@ -2311,6 +2311,11 @@ public class LightAnalysisModeTestGenerated extends AbstractLightAnalysisModeTes
             runTest("compiler/testData/codegen/box/callableReference/kt46902.kt");
         }
 
+        @TestMetadata("kt47988.kt")
+        public void testKt47988() throws Exception {
+            runTest("compiler/testData/codegen/box/callableReference/kt47988.kt");
+        }
+
         @TestMetadata("nested.kt")
         public void testNested() throws Exception {
             runTest("compiler/testData/codegen/box/callableReference/nested.kt");