Remove handling of eStateStopped from NativeProcessLinux::Resume

Summary:
NPL::Resume attempted to handle eStateStopped as a resume action. However:
- GDBRemoteCommunicationServerLLGS (the only user of NPL) never sets this action
- it could set this action in response to a vCont:t packet, but LLDB never produces this packet
- gdb-remote protocol documentation says vCont:t packet is used only in non-stop mode, but LLDB
  does not support non-stop mode
- even if LLDB supported non-stop mode, this implementation of eStateStopped does something
  different from what the spec says it should (according to spec, it should stop the specified
  thread, but this seems to want to stop all threads).

Given the facts above, I believe we should remove this unused and untested code, as it probably
doesn't even work and removing it makes the rest of the code noticably simpler.

Reviewers: ovyalov, chaoren

Subscribers: lldb-commits

Differential Revision: http://reviews.llvm.org/D9657

llvm-svn: 237103