llvm-rs-as: Wrap bitcode with the RS bitcode wrapper.

Change llvm-rs-as and llvm-rs-cc to use the same code path when it comes
to writing bitcode.  As a result llvm-rs-as can take a *.ll file and
output a *.bc file containing the RenderScript bitcode wrapper, so that
code produced by llvm-rs-as can be read by bcinfo.

Change-Id: I3f9aed3764cbafddb219a21abd89490ca8019bc1
8 files changed