Put default value to vars iff they are not boxed

#KT-24672 Fixed

compiler/testData/codegen/bytecodeText/localInitializationLVT/inlineClassVar.kt

@@ -0,0 +1,12 @@
+// IGNORE_BACKEND: JVM_IR
+
+fun test(): UInt {
+    var c: UInt
+    run {
+        c = 1u
+    }
+    return c
+}
+
+// 1 ASTORE 0
+// 1 LOCALVARIABLE c Lkotlin/jvm/internal/Ref\$IntRef; L1 L11 0