Add dist-for-goals for droiddoc docs.zip

Old droiddoc will install the *-docs.zip & API files to the dist.

And also remove INTERNAL_PLATFORM_*API_FILE variables from config.mk and
get rid of the dependencies on api-stubs, system-api-stubs, test-api-stubs
timestamp.

Test: m -j api-stubs-docs
Bug: b/70351683
Change-Id: I08923bb5f62d2f55961d9a2865723d7b3fae7206
Merged-In: I08923bb5f62d2f55961d9a2865723d7b3fae7206
diff --git a/core/soong_java_prebuilt.mk b/core/soong_java_prebuilt.mk
index 36a71e3..63a1e2e 100644
--- a/core/soong_java_prebuilt.mk
+++ b/core/soong_java_prebuilt.mk
@@ -30,6 +30,7 @@
 
 ifdef LOCAL_DROIDDOC_DOC_ZIP
 $(eval $(call copy-one-file,$(LOCAL_DROIDDOC_DOC_ZIP),$(OUT_DOCS)/$(LOCAL_MODULE)-docs.zip))
+$(call dist-for-goals,docs,$(OUT_DOCS)/$(LOCAL_MODULE)-docs.zip)
 endif
 
 ifdef LOCAL_SOONG_JACOCO_REPORT_CLASSES_JAR