[commonizer] Don't commonize "tailrec" and "external" modifiers

expect external and tailrec were prohibited
in previous commit.

^KT-58536

native/commonizer/testData/propertyCommonization/specifics/commonized/common/package_root.kt

@@ -13,5 +13,7 @@ expect var inlineProperty6: Int
 expect var inlineProperty7: Int
 expect var inlineProperty8: Int
 
-expect external val externalProperty1: Int
+expect val externalProperty1: Int
 expect val externalProperty2: Int
+
+expect var externalSetGet: Int

native/commonizer/testData/propertyCommonization/specifics/original/js/package_root.kt

@@ -28,3 +28,7 @@ inline var inlineProperty8
 
 external val externalProperty1: Int
 external val externalProperty2: Int
+
+var externalSetGet: Int
+    external get
+    external set

native/commonizer/testData/propertyCommonization/specifics/original/jvm/package_root.kt

@@ -28,3 +28,7 @@ var inlineProperty8
 
 external val externalProperty1: Int
 val externalProperty2: Int = 1
+
+var externalSetGet: Int
+    external get
+    external set