Add min_sdk_version:R to updatable apexes

APEXes introduced in R need to set min_sdk_version to ensure that they
are built against correct version(30 or R) of stubs (libc/liblog/...).

Bug: 152655956
Test: /vendor/google/build/build_mainline_modules.sh
Change-Id: I4a893c34b09334eea124266287301e479b9e8a59

Tethering/apex/Android.bp

@@ -17,6 +17,7 @@
 apex {
     name: "com.android.tethering",
     updatable: true,
+    min_sdk_version: "R",
     java_libs: ["framework-tethering"],
     apps: ["Tethering"],
     manifest: "manifest.json",