Add $(SOONG_OUT_DIR)/ndk/% to artifact whitelist

This commit adds `$(SOONG_OUT_DIR)/ndk/%` to artifact whitelist so that
when NDK stub libraries won't be blocked by artifact path requirements.

This commit does not break the integrity of artifact path requirements
because they are not installed to devices.

Bug: 123053270
Bug: 119084334
Test: lunch aosp_crosshatch-userdebug
Change-Id: Ieea76a8126269f53b0a58bd069b449a9f9b1263a