This eliminates some overhead, because the compiler doesn't need to
consider these functions throwing.

Some optimized implementations of memcmp() may not start from the
beginning of the string, and may thus segfault.

Make sure we get a UTF-8 encoded string.

Clean up the process before exiting.

Replaced all occurrences of g_error() with MPD_ERROR() located in a new header
file 'mpd_error.h'. This macro uses g_critical() to print the error message
and then exits gracefully in contrast to g_error() which would internally call
abort() to produce a core dump.

The macro name is distinctive and allows to find all places with dubious error
handling. The long-term goal is to get rid of MPD_ERROR() altogether. To
facilitate the eventual removal of this macro it was added in a new header
file rather than to an existing header file.

This fixes #2995 and #3007.

MPD doesn't have child processes anymore, and thus we're not expecting
to receive SIGCHLD very often.  Since hard disk access isn't
interrupted by signals anyway, we don't need those excessive checks.

After we've been hit by Large File Support problems several times in
the past week (which only occur on 32 bit platforms, which I don't
have), this is yet another attempt to fix the issue.

Use GLib the logging functions g_debug(), g_error() instead.

This updates the copyright header to all be the same, which is
pretty much an update of where to mail request for a copy of the GPL
and the years of the MPD project. This also puts all committers under
'The Music Player Project' umbrella. These entries should go
individually in the AUTHORS file, for consistancy.

WIN32 doesn't have POSIX signals.  Disable the code.  For a complete
port, we will have to implement the WIN32 equivalent.

Nobody is using the signal_check library anymore.

This patch also removes the SIGUSR1 handler.

The signal_check library went out of order when we started using the
GLib main loop.  Convert the SIGHUP handler to use event_pipe instead.

We don't need to use asynchronous events to quit MPD, we can just call
g_main_loop_quit() inside the handler.

We have no child processes anymore.  Remove the SIGCHLD handler.

The SIGHUP handler was used by the update process to make the main
process re-read the database.  We don't need this anymore, since the
update takes place in a thread now.

Most of these functions were obsoleted when we switched to threaded
MPD.

Yet another CamelCase removal patch.

Taming the directory.c monster, part II: move the database management
stuff to database.  directory.c should only contain code which works
on directory objects.

When there are standardized headers, use these instead of the bloated
os_compat.h.

The source directory.c mixes several libraries: directory object
management, database management and database update, resulting in a
1000+ line monster.  Move the whole database update code to update.c.

A lot of the preparation was needed (and done in previous
months) in making update thread-safe, but here it is.

This was the first thing I made work inside a thread when I
started mpd-uclinux many years ago, and also the last thing I've
done in mainline mpd to work inside a thread, go figure.