[JVM IR] Do not generate clinit as enclosing method.

The JVM and newer Android runtimes treats that the same as if
there is no enclosing method. However, older Android runtimes
for Android 5 and 6 throw exceptions on reflective access
and even older runtimes have different behavior. To avoid
those issues, exclude <clinit> from enclosing method attributes.

^ KT-48754 Fixed

compiler/testData/codegen/bytecodeText/outerClass/classInClinit.kt

@@ -0,0 +1,7 @@
+// FILE: test.kt
+
+// This should *not* have enclosing method <clinit>. See https://youtrack.jetbrains.com/issue/KT-48754.
+val a = {}
+
+// @TestKt$a$1.class:
+// 1 OUTERCLASS TestKt null