Add 'disableDesignatedInitializerChecks' .def file flag

When enabled for an Objective-C library, compiler would permit to call
a constructor of a class from this library as super-constructor even if
it is not marked as designated.

Fix #1539

shared/src/main/kotlin/org/jetbrains/kotlin/konan/util/DefFile.kt

@@ -99,6 +99,10 @@ class DefFile(val file:File?, val config:DefFileConfig, val manifestAddendProper
         val exportForwardDeclarations by lazy {
             properties.getSpaceSeparated("exportForwardDeclarations")
         }
+
+        val disableDesignatedInitializerChecks by lazy {
+            properties.getProperty("disableDesignatedInitializerChecks")?.toBoolean() ?: false
+        }
     }
 }