Restore the "mpcdec" decoder plugin that was accidently broken since
commit 8ead8f7e.

Make the third argument to AC_CHECK_LIB() non-empty to disable its
default handler.

The header glib_compat.h is now obsolete and can be removed.

This plugin has been defunct ever since Last.fm changed their
protocol.  Since there is no volunteer willing to fix the plugin, I'm
removing it now.

Remove all #ifdefs.  Old versions of libpulse are not being tested,
and thus I'm removing support.

Remove the runtime check for eventfd(), hard-code the feature once
it's been selected at compile time.  The class WakeFD is splitted into
EventFD and EventPipe, using WakeFD as a macro diversion.

Now that even Debian stable has picked up version 0.8, we can safely
make this a requirement, and remove a lot of old cruft.

This old version has been obsolete for many years - time to remove it.

This plugin is cumbersome to support, now that MPD is migrating away
from GLib and the GLib event loop.  It has no practical advantages
over the CURL plugin.  Soup requires the bloated GType library.

This plugin has been in MPD for three years, and it has never worked.
Enough!

The hardware is obsolete, and the product does not exist anymore on
the Hauppauge web site.  Let's see if anybody complains about the
removal.

Eliminate the fallback strndup() and strnlen() implementations.

This is the version present in Ubuntu Oneiric, the oldest distribution
with gcc 4.6.  Debian Squeeze is off target, because it has gcc 4.4,
which is unable to compile MPD anyway.

This commit drops all API compatibility hacks for older versions.

The underlying library has been obsolete for many years.

Usually, when strndup() is not available, strndup() isn't either,
because both are POSIX 2008.

The libwrap version on Mac OS X is broken, it will not work with C++
due to broken function prototypes.

We're going to use Vista features soon.  Sorry for those poor people
still on XP (or Windows, anyway).

This patch also adds extern "C" { } wrapper around string_util.h
to allow its usage in C++ code