FreeBSD: Replace GetSignalInfo with GetLwpInfo

For thread support we are going to need other members of struct
ptrace_lwpinfo.


git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@186505 91177308-0d34-0410-b5e6-96231b3b80d8
Correct comment to match class name



git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@186509 91177308-0d34-0410-b5e6-96231b3b80d8