Create a header-only library for atrace in platform NDK builds

App NDK has access to libandroid for tracing APIs in trace.h. These APIs
wrap libcutils atrace methods.
Vendor does not have access to libandroid, but does have access to
libcutils.
To keep the code portable, libandroid_trace is created for the
platform NDK. Now both variants can include android/trace.h, use the
same APIs, and just link with the different libraries(libandroid for
apps, libandroid_trace and libcutils for platform code).

Test: Build and run aidl interfaces(-ndk and -ndk_platform) with these tracing calls.
Bug: 128533039
Change-Id: Iba5917a06fd58573265dcaf5658c4958d8f591dc