Report the result of waitpid() a little more clearly as well as clearly logging the process status.

git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@207698 91177308-0d34-0410-b5e6-96231b3b80d8
Allow for a task port to change when we exec. 

git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@207699 91177308-0d34-0410-b5e6-96231b3b80d8
Sometimes when launching through a shell, we can run into cases where the /bin/sh or /usr/bin/arch can crash the process due to security measures. Now we correctly report when a process exited in the process of launching so we can show the reason why it crashed instead of just showing “initial process state wasn't stopped: exited”.

git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@207700 91177308-0d34-0410-b5e6-96231b3b80d8
Merge llvm.org r207700 into dev-tfiala-native-protocol-linux-x86_64
Fixed up crash in NativeProcessLinux launch inferior startup.

Made NativeProcessLinux constructor private. Moved inferior launching
and inferior attaching into separate private methods that occur after
clean construction. This fixes a crash in
NativeProcessLinux->shared_from_this () that was previously accessed
during construction (via thread creation).

Added new thread tracking in the launch inferior sequence, fixing
NPL::Resume ().  Added private NPL::AddThread () method.

Added NPL::HasThreadNoLock () private helper.

Added dummy impls to NativeThreadLinux for GetRegisterContext(),
SetWatchpoint() and RemoveWatchpoint().

Added logging to llgs vCont handling.