Set min_sdk_version to be part of mainline modules

Modules contributing mainline modules (APK/APEX) should set
min_sdk_version as well as apex_available.

For now setting min_sdk_version doesn't change build outputs.
But build-time checks will be added soon.

Exempt-From-Owner-Approval: CP from AOSP

Bug: 152655956
Test: m
Change-Id: I2735a96ebd7eb88a39eeeba149cb5cbf1daf1308
diff --git a/arm-wt-22k/Android.bp b/arm-wt-22k/Android.bp
index a006af7..bf45b0d 100644
--- a/arm-wt-22k/Android.bp
+++ b/arm-wt-22k/Android.bp
@@ -121,6 +121,7 @@
         "//apex_available:platform",
         "com.android.media",
     ],
+    min_sdk_version: "29",
 }
 
 cc_library {