libports: add libc's rpc framework headers

Certain rpc headers are needed for compiling getaddrinfo.c. Unfortunatly
that means we have to generate _a few_ header files which we do when we
prepare the libc.

These header files need to be created before the symlinks. Also, some of
these header files depend on a patch. Therefore we apply the patches
first, generate the header files and in the end we create the symlinks.
Noux: add noux-pkg/etc

This package provides files in /etc which are needed for domain
resolving etc. pp.
Noux: add noux-pkg/lynx

Explanation why --disable-rpath-hack is needed:

When building on pistachio_x86 $(LDFLAGS) contains '-L[...]/l4/lib'
which will be transformed by autoconf to '-rpath [...]/l4/lib'.
Now the problem at hand is that we pretend to be FreeBSD when we are
actually not. So autoconf assumes it is valid to use '-path'  when it
is actually not.

Also we use zlib for (de)compressing gzipped streams/files instead of
calling gzip as this currently somewhat buggy.
Noux: rename noux-pkg/gnu-netcat

The other GNU based packages do not have a gnu- prefix either.
Noux: use counter for gettimeofday()

There are certain issues which currently prevent us from writing proper
implementations for time related functions. For now we provide a simple
counter instead to make programms like ping(1) happy.
Noux: add F_GETFL handling to terminal_io_channel

There are certain programms which check if an fd is open by calling
fcntl(fd, F_GETFL, ...). So to keep them happy we return true if
such an request was done to our terminal fd's.
Noux: add FIONBIO handling support to libc_noux
Noux: add F_SETFL to libc_noux's fcntl()

Among other things it is used to set non-blocking mode, so we should
support it (e.g. fcntl(d, F_SETFL, fl | O_NONBLOCK)).
Noux/net: add F_SETFL sup. to socket_io_channel

netcat uses F_SETFL with O_NONBLOCK to set the socket to non-blocking
mode.
Noux/net: add explicit clear_unblock() call...

... and disable a few debug messages.
Noux/net: several changes to Socket_io_channel

These changes include the handling of the FIONBIO ioctl() request
an also fixes a bug regarding the io_check_unblock() method.

check_unblock() did not use the arguments at all, which results in
wrong behaviour in certain situatutions.

Socket_io_channel's write() method did not implement the right
interface and was next to useless. Luckily, you normally do not use
write(1) on a socket.
Noux: add cleanup_socket_descriptor()

This function removes all currently used socket descriptors from the
socket descriptor registry. It is only called when a child is exiting.
Noux/net: add reset_all() method to sd registry

This method is called when a child is exiting to remove all remaining
sockets from the socket descriptor registry to close all sockets.
Noux: add timeout handling to select()

Previously there was not actual timeout handling. If a select() call
set an timeout it would be set to zero instead and was always handled
as blocking i/o. While this works fine for file descriptors which will
be triggerd externally (for example vim through terminal i/o) it does
not work at all for socket descriptors and network operations in
general.

So this commit introduces proper timeout handling and changes the
behaviour of SYSCALL_SELECT so that it now returns more than just one
descriptor at a time.

noux/minimal and noux/net now depend on thread and alarm libraries.
Noux: add is_nonblocking() method

Certain programs tend to set their sockets non-blocking.
As previously descriptors in Noux were only blocking we now introduce
a method to mark the used Io_channel as non-blocking.
Noux: remove {get,free}addrinfo implementation

Remove all unused code because we now use the libc's implementation
only.
libports: add libc-rpc
libports: add needed files to libc-net
Noux: blacklist '/dev/null' in libc_noux

'/dev/null' is provided by another libc plugin. We do not want libc_noux
to block our plugin because libc_noux' supports_open() always returns
true.
libports: add poll() to libc

Implements poll() via select() for certain programs like OpenSSH
which need it.

(This implementation is actually based OpenSSHp's compat function.)