Simplify indirect rld_map for mips (rework r192408).

Just pass a Target* into ObjectFileELF::GetImageInfoAddress so that
it can do the extra dereference necessary on MIPS, instead of passing
a flag back to the caller.

Review: http://llvm-reviews.chandlerc.com/D1899


git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@192469 91177308-0d34-0410-b5e6-96231b3b80d8