Update RenderScript build rules for rebase to LLVM r256229

http://b/26987366

- Use clang-2690385 to build RenderScript toolchain.
- Use armv7-linux-androideabi as the triple used to build RenderScript
  runtime libraries.

Change-Id: I582e8b25bbc38b101a2e765028ed61edbce7bdc2
4 files changed