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
Change-Id: I478014d66fdfbe61b025960ff27b0b5e57c6f458
diff --git a/stable/Android.bp b/stable/Android.bp
index 5e54e9a..0af6f1c 100644
--- a/stable/Android.bp
+++ b/stable/Android.bp
@@ -67,7 +67,7 @@
     ],
     static_libs: [
         "libgflags",
-        "libupdate_engine_stable-V1-ndk_platform",
+        "libupdate_engine_stable-V1-ndk",
     ],
     srcs: [
         "update_engine_stable_client.cc",