MFC r262528: Update LLDB snapshot to upstream r202189

  Highlights include (upstream revs in parens):

  - Improvements to the remote GDB protocol client
    (r196610, r197579, r197857, r200072, and others)

  - Bug fixes for big-endian targets
    (r196808)

  - Initial support for libdispatch (GCD) queues in the debuggee
    (r197190)

  - Add "step-avoid-libraries" setting
    (r199943)

  - IO subsystem improvements (including initial work on a curses gui)
    (r200263)

  - Support hardware watchpoints on FreeBSD
    (r201706)

  - Improved unwinding through hand-written assembly functions
    (r201839)

  - Handle DW_TAG_unspecified_parameters for variadic functions
    (r202061)

  - Fix Ctrl+C interrupting a running inferior process
    (r202086, r202154)

  - Various bug fixes for memory leaks, LLDB segfaults, the C++ demangler,
    ELF core files, DWARF debug info, and others.

Sponsored by:	DARPA, AFRL
MFC r263678: lldb: Invoke PT_KILL from ProcessPosix::DoDestroy

  We previously sent SIGKILL to the debuggee in DoDestroy, but did not
  actually detach or kill via ptrace.  It seems that this somehow didn't
  matter on Linux, but did on FreeBSD.

  This would happen when quitting LLDB while stopped at a breakpoint, for
  example.  The debuggee remained stopped in ptrace (with the signal
  either pending or lost).  After a timeout of a second or two LLDB exits,
  which caused the debuggee to resume and dump core from an unhandled
  SIGTRAP.

  BringProcessIntoLimbo is a poorly named wrapper for ptrace(PT_KILL)
  which is the desired behaviour from DoDestroy.

  http://llvm.org/pr18894

Sponsored by:	DARPA, AFRL
MFC r268527: Remove unused readline header