Remove ndk_platform backend. Use the ndk backend. am: 547a1a4e1f am: 0c563ed7d9

Original change: https://android-review.googlesource.com/c/platform/system/libfmq/+/1867815

Change-Id: Iabf4a7ee8e535b9dcf7d73a745093e58f9cbfa99
tree: 54272e31b0b888a0b6cfb1f0b591c2462a51546c
  1. base/
  2. benchmarks/
  3. fuzzer/
  4. include/
  5. tests/
  6. Android.bp
  7. EventFlag.cpp
  8. FmqInternal.cpp
  9. OWNERS
  10. PREUPLOAD.cfg
  11. TEST_MAPPING