lldb::SBTarget and lldb::SBProcess are now thread hardened. They both still

contain shared pointers to the lldb_private::Target and lldb_private::Process
objects respectively as we won't want the target or process just going away.

Also cleaned up the lldb::SBModule to remove dangerous pointer accessors.

For any code the public API files, we should always be grabbing shared 
pointers to any objects for the current class, and any other classes prior
to running code with them.

llvm-svn: 149238