Fixed gdbremote $A packet handling to properly support multiple args on
the commandline.

Moved GetExitStatus()/SetExitStatus() definition into
NativeProcessProtocol.cpp.

Added logging to NPP::SetExitStatus().

Added retrieval of exit description to NPP::GetExitStatus().

Added logging of arguments passed to
NativeProcessLinux::LaunchProcess().

Added proper handling of exit status from NativeProcessLinux.  Added
proper handling of exiting threads in NativeProcessLinux.

Fixed bugs in saving of thread state in NativeThreadLinux.