vendor/widevine: Set LOCAL_SDK_VERSION where possible.

This change sets LOCAL_SDK_VERSION for all packages where
this is possible without breaking the build, and
LOCAL_PRIVATE_PLATFORM_APIS := true otherwise.

Setting one of these two will be made required soon, and this
is a change in preparation for that. Not setting LOCAL_SDK_VERSION
makes the app implicitly depend on the bootclasspath, which is
often not required. This change effectively makes depending on
private apis opt-in rather than opt-out.

Test: make relevant packages
Bug: 73535841
Change-Id: I1c0366e78fb44f06bc07329866440097275f5b51

libwvdrmengine/test/castv2/Android.mk

@@ -13,6 +13,7 @@ LOCAL_SRC_FILES := $(call all-java-files-under, src)
 LOCAL_JAVA_LIBRARIES := com.android.mediadrm.signer org.apache.http.legacy
 
 LOCAL_PACKAGE_NAME := CastSignAPITest
+LOCAL_PRIVATE_PLATFORM_APIS := true
 
 include $(BUILD_PACKAGE)
 

libwvdrmengine/test/java/Android.mk

@@ -14,8 +14,7 @@ LOCAL_DEX_PREOPT := false
 # When built, explicitly put it in the data/app partition.
 LOCAL_MODULE_PATH := $(TARGET_OUT_DATA_APPS)
 
-# TODO: This test app depends on framework implementation details.
-# LOCAL_SDK_VERSION := current
+LOCAL_SDK_VERSION := current
 
 include $(BUILD_PACKAGE)