Add Automotive OS API 29 stubs to platform SDK optionals.

Android Automotive OS stubs (android.car-stubs.jar) is used
to compile apps against Car API.

NOTE: We tried using
${OUT_DIR}/target/common/obj/JAVA_LIBRARIES/android.car-stubs_intermediates/classes.jar,
but it doesn't work because car-stubs are not generated when building
regular Android SDK for phones.

Bug: 154653660
Test: m -j
Test: m -j dist
Test: 1. $ ./build/soong/soong_ui.bash --make-mode TARGET_PRODUCT=sdk_phone_armv7 \
             TARGET_BUILD_VARIANT=userdebug win_sdk dist DIST_DIR=dist-mine sdk_repo
      2. Copy and unzip dist-mine/android-sdk_eng.zhomart_windows.zip to
         $HOME/Android/Sdk (replaced the existing Sdk forlder)
      3. Created a sample app, used "android.car.Car" and verified it
         compiles, runs and connects to the car service.
Change-Id: I1913fd89cf1cd702b3b5b3f386cf3693a5042eea

build/optional.json

@@ -4,6 +4,11 @@
     "jar": "org.apache.http.legacy.jar",
     "manifest": false
   },
+  {
+    "name": "android.car",
+    "jar": "android.car.jar",
+    "manifest": false
+  },
   {
     "name": "android.test.mock",
     "jar": "android.test.mock.jar",

build/sdk.atree

@@ -172,6 +172,8 @@ ${OUT_DIR}/target/common/obj/PACKAGING/android_jar_intermediates/android-stubs-s
 # optional API files.
 development/build/optional.json                                                               platforms/${PLATFORM_NAME}/optional/optional.json
 ${OUT_DIR}/target/common/obj/JAVA_LIBRARIES/org.apache.http.legacy.stubs_intermediates/classes.jar  platforms/${PLATFORM_NAME}/optional/org.apache.http.legacy.jar
+# Android Automotive OS stubs.
+prebuilts/sdk/29/public/android.car.jar                                                       platforms/${PLATFORM_NAME}/optional/android.car.jar
 # deprecated APIs
 ${OUT_DIR}/target/common/obj/JAVA_LIBRARIES/android_uiautomator_intermediates/classes.jar     platforms/${PLATFORM_NAME}/uiautomator.jar
 # Test APIs