Download symbol file for .oat files on android

Download symbol file for .oat files on android

On android .oat files (compiled java code) don't have symbol
information but on SDK 23+ it can be generated by the oatdump tool
(based on the dex information).

This CL adds logic to download this information and store it in the
module cache.

Differential revision: http://reviews.llvm.org/D11936

llvm-svn: 244738