Add 'libports/include/pcre' to '.gitignore'
Enable gdb_monitor for NOVA
NOVA: Use thread_state with all registers
Propagate result of cpu_session::state call

State may fail, don't just return just true.
NOVA: extend cpu_session with synchronous pause

The kernel provides a "recall" feature issued on threads to force a thread into
an exception. In the exception the current state of the thread can be obtained
and its execution can be halted/paused.

However, the recall exception is only delivered when the next time the thread
would leave the kernel. That means the delivery is asynchronous and Genode has
to wait until the exception triggered.

Waiting for the exception can either be done in the cpu_session service or
outside the service in the protection domain of the caller.

It turned out that waiting inside the cpu_service is prone to deadlock the
system. The cpu_session interface is one of many session interfaces handled by
the same thread inside Core.

Deadlock situation:
* The caller (thread_c) to pause some thread_p manages to establish the call
  to the cpu_session thread_s of Core but get be interrupted before issuing
  the actual pause (recall) command.
* Now the - to be recalled thread_p - is scheduled and tries to invoke another
  service of Core, like making log output.
* Since the Core thread_s is handling the session request of thread_c, the
  kernel uses the timeslice of thread_p to help to finish the request handled
  by thread_s.
* Thread_s issues the actual pause/recall on thread_p and blocks inside Core
  to wait for the recall exception to be issued.
* thread_p will leave not the kernel before finishing it actual IPC with
  thread_s which is blocked waiting for thread_p.

That is the reason why the waiting/blocking for the recall exception taking
place must be done on NOVA in the context of the caller (thread_1).

Introduce a pause_sync call to the cpu_session which returns a semaphore
capability to the caller. The caller blocks on the semaphore and is woken up
when the pager of thread_p receives the recall exception with the state of
thread_p.
NOVA: implement pause using recall kernel feature
NOVA: tunnel thread start parameters via state()

The cpu_session interface fails to be virtualized by gdb_monitor because
platform-nova uses an extended nova_cpu_session interface.

The problem was that threads have been created directly at core without
knowledge of gdb_monitor. This lead to the situation that gdb_monitor didn't
know of all threads to be debugged.

Tunnel the additional parameters required on base-nova through the state()
call of the cpu_session interface before the thread actual is started.
NOVA: setup all exception handlers of a thread
NOVA: add single-step support used by gdb

Fixes #336
Noux: add proper errno handling to network funcs

Programs use the errno value to check which error exactly occured.
It is mandatory for non-blocking I/O, e.g. connect() gets the current
state of the connection by looking at the returned errno values.

Fixes #337.
Noux: override uid/gid in SYSCALL_STAT

Change the uid/gid entries in the stat syscall to have the same values
on all filesystems that are used in the current noux-instance according
to the specified values in noux' config.

Fixes #338.
Noux: store environment variables zero-separated

With this patch environment variables always get stored as zero-separated
strings in buffers of type 'Sysio::Env'. This fixes the problem that
environment variables with non-alphanumeric characters did not get set
correctly in child processes.

Fixes #340.