JVM_IR: partially fix inline methods using captured crossinline lambdas

The fields containing crossinline lambdas should be package-private to
avoid generating synthetic accessors, which break object regeneration.

Note that the inline methods cannot actually be called, as call sites
will attempt to read the captured lambda from a field through a *copy*
of the local containing the object, so these reads will not be inlined,
causing an exception at runtime:

    inline fun f(crossinline g: () -> Unit) = object : I {
        inline fun h() = g()
        // effectively `val tmp = this; return tmp.$g()`:
        override fun run() = h()
    }

    f {}.run() // NoSuchFieldError: $g

This particular example can be fixed by reusing locals for receiver
parameters in IrInlineCodegen, but explicitly assigning `this` to
another variable and calling an inline method on it will break it again.
(This is only applicable to the JVM_IR backend, as the non-IR one fails
to generate `f` at all for some other reason.)

compiler/tests/org/jetbrains/kotlin/codegen/BlackBoxInlineCodegenTestGenerated.java

@@ -276,6 +276,11 @@ public class BlackBoxInlineCodegenTestGenerated extends AbstractBlackBoxInlineCo
             runTest("compiler/testData/codegen/boxInline/anonymousObject/superConstructorWithObjectParameter.kt");
         }
 
+        @TestMetadata("withInlineMethod.kt")
+        public void testWithInlineMethod() throws Exception {
+            runTest("compiler/testData/codegen/boxInline/anonymousObject/withInlineMethod.kt");
+        }
+
         @TestMetadata("compiler/testData/codegen/boxInline/anonymousObject/enumWhen")
         @TestDataPath("$PROJECT_ROOT")
         @RunWith(JUnit3RunnerWithInners.class)