Set thread names on FreeBSD

Also move the logic to shorten thread names from linux/Host.cpp to a new
SetShortThreadName as both FreeBSD and Linux need the functionality.


git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@187149 91177308-0d34-0410-b5e6-96231b3b80d8
4 files changed