Change DecodeProcessInfoResponse to set the ProcessInfo's architecture 
if the remote stub provided enough information to identify it in the
qProcessInfo packet response.  (e.g. for an Apple device where we know 
it is Mach-O, the cpu type & cpu sub type).
<rdar://problem/15847901> 


git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@200253 91177308-0d34-0410-b5e6-96231b3b80d8