Remove ndk_platform backend. Use the ndk backend.

The ndk_platform backend will soon be deprecated because the ndk backend
can serve the same purpose. This is to eliminate the confusion about
having two variants (ndk and ndk_platform) for the same ndk backend.

Bug: 161456198
Test: m
Merged-In: Ifadc89ec1cdb32dc39d5639665167c7bae336836
Change-Id: I99947e7fc58b5f6ab7d75f2af63b6bf9384917c3
1 file changed