Add prebuilts/ndk/android-ndk-r8

Populate it with released NDK r8b at
http://developer.android.com/tools/sdk/ndk/index.html

Note that r8b contains two gnu-libstdc++ for each compiler
version, which changes directory structure as follow:

  android-ndk-r8/sources/cxx-stl/gnu-libstdc++/4.4.3, and
  android-ndk-r8/sources/cxx-stl/gnu-libstdc++/4.6

For the sake of backward scripting compatibility, only content
of 4.4.3 version is copied.  GCC 4.6 can take it, but not
the other way around.

Change-Id: I78d288b64c17daab005652dd48d6ce25629c6996
13816 files changed