Put default value to vars iff they are not boxed

#KT-24672 Fixed

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

@@ -0,0 +1,23 @@
+// IGNORE_BACKEND: JVM_IR
+
+fun test(): Char {
+    var c: Char
+    val l = Any()
+    val l1 = Any()
+    val l2 = Any()
+    val l3 = Any()
+    val l4 = Any()
+    val l5 = Any()
+    val l6 = Any()
+    val l7 = Any()
+    val l8 = Any()
+    val l11 = Any()
+    val l12 = Any()
+    val l13 = Any()
+    val l14 = Any()
+    c = '1'
+    return c
+}
+
+// 2 ISTORE 0
+// 1 LOCALVARIABLE c C L1 L16 0