Use underlying type when computing type mapping mode for inline classes

compiler/testData/codegen/box/inlineClasses/kt26103_original.kt

@@ -0,0 +1,13 @@
+// !LANGUAGE: +InlineClasses
+// WITH_RUNTIME
+// IGNORE_BACKEND: JVM_IR
+
+inline class Foo<T>(val x: Int)
+
+class Bar(val y: Foo<Any>)
+
+fun box(): String {
+    if (Bar(Foo<Any>(42)).y.x != 42) throw AssertionError()
+
+    return "OK"
+}