Include online-system-api-sdk only if it's requested.

We can remove the conditional once the build is fixed.
Change-Id: I367504cf378280cc0a8eff0a7a3eb0936a4828c0
diff --git a/Android.mk b/Android.mk
index e26eff3..61181f7 100644
--- a/Android.mk
+++ b/Android.mk
@@ -844,6 +844,8 @@
 include $(BUILD_DROIDDOC)
 
 # ==== docs for the web (on the androiddevdocs app engine server) =======================
+# TODO: Fix the System API docs build.
+ifneq ($(filter online-system-api-sdk-docs,$(MAKECMDGOALS)),)
 include $(CLEAR_VARS)
 
 LOCAL_SRC_FILES:=$(framework_docs_LOCAL_SRC_FILES)
@@ -874,6 +876,7 @@
 LOCAL_UNINSTALLABLE_MODULE := true
 
 include $(BUILD_DROIDDOC)
+endif  # online-system-api-sdk-docs in make command line.
 
 # ==== docs for the web (on the devsite app engine server) =======================
 include $(CLEAR_VARS)