Support platformStatic for properties

#KT-5766 Fixed

compiler/testData/codegen/boxWithStdlib/platformStatic/propertyAsDefault.kt

@@ -0,0 +1,11 @@
+import kotlin.platform.platformStatic
+
+object X {
+    platformStatic val x = "OK"
+
+    fun fn(value : String = x): String = value
+}
+
+fun box(): String {
+    return X.fn()
+}