Mark updatable APEXes

Mark updatable APEXes as updatable: true so that they are opted-out from
optimizations that make sense only for non-updatable modules; such as
symlinking to the libs in the system partition.

Bug: 149805758
Test: m and check that there is no symlink from the APEX to the system
partition.

Exempt-From-Owner-Approval: cherry-pick from internal

Merged-In: Idb55300a60a261c7bb6359439ed220ff51fcf06c
(cherry picked from commit 8201bdfab0)
Change-Id: Idb55300a60a261c7bb6359439ed220ff51fcf06c

apex/sdkextensions/Android.bp

@@ -27,6 +27,7 @@ apex {
 
 apex_defaults {
     name: "com.android.sdkext-defaults",
+    updatable: true,
     java_libs: [ "framework-sdkextensions" ],
     prebuilts: [
         "derive_sdk.rc",

packages/Tethering/apex/Android.bp

@@ -16,6 +16,7 @@
 
 apex {
     name: "com.android.tethering",
+    updatable: true,
     java_libs: ["framework-tethering"],
     apps: ["Tethering"],
     manifest: "manifest.json",