Update RenderScript build config and definitions.

Bug: 38342163

  - obj/lib is deprecated and TARGET_OUT_INTERMEDIATE_LIBRARIES will be
  removed. We need to use per-module intermediates directory instead.
  - prebuilts/ndk/current folder is gone. For libm and libc, we just
  need ndk/r10 as stub libs for linking.

Test: mm and made sure this does not affect on device target.
Test: make -j50 FORCE_BUILD_RS_COMPAT=true RSTest_Compat works as
expected.

Change-Id: I8fbf5c10322707849a23c6b0dacc28b028db451e