Add setting of lldb thread names on Linux.

Patch by Mike Sartain.


git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@181722 91177308-0d34-0410-b5e6-96231b3b80d8
Fixed build break introduced by r181717
- added missing ConstString header
- moved "using lldb*" statements to OS-independent section




git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@181724 91177308-0d34-0410-b5e6-96231b3b80d8
Fixed expression evaluation with convenience registers.

- Also improved test coverage for passing tests to include expr/x
and a sanity check for $eax as the lower half of $rax.


git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@181727 91177308-0d34-0410-b5e6-96231b3b80d8