Move the rest of the HostInfo functions over.

This should bring HostInfo up to 99% completion.  The remainder
of code in Host will be split into instantiatable classes
representing host processes, threads, dynamic libraries, and
process launching strategies.

git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@216230 91177308-0d34-0410-b5e6-96231b3b80d8