With this patch, the 'futex' syscall gets used for blocking and unblocking
of threads in the Linux-specific lock implementation.
The 'Native_thread_id' type, which was previously used in the
lock-internal 'Applicant' class to identify a thread to be woken up,
was not suitable anymore for implementing this change. With this patch,
the 'Thread_base*' type gets used instead, which also has the positive
effect of making the public 'cancelable_lock.h' header file
platform-independent.
Fixes#646.
In the recent change of the RPC-entrypoint destruction, the
'~Rpc_entrypoint' calls 'Thread_base::join'. Hence, we need to provide
an implementation wherever RPC entrypoints are used.
Martin Stein
Christian Prochaska
Norman Feske