If a log message does not include a newline character, append it.

Only include headers which are really needed.  os_compat.h aimed to
make MPD easily portable, but was never actually made portable.

gmtime_r() is not available.

These methods are unused.

Fix for bug #1491.

I tried to search for a certain composer in my collection, but only
non-mp4 files showed up. The source code reveals that this tag is not
read. This can be fixed by reading the 'Writer' tag field, in
mp4_plugin.c, in function mp4_load_tag.

I actually tried this, and after compiling with those lines added,
also mp4 (.m4a) files showed up when searching for a composer.

All archive plugins used to overwrite $MPD_LIBS, ignoring the existing
value.  Make them append instead, keeping the old value.

Don't bother to look for libbz2, libzzip and libiso9660 if the plugins
are disabled.

We're now using GLib threading.

Replaced myFgets() with fgets() + g_strchomp().

g_ascii_isspace() includes \r and \n.  This means that lines from a
text file don't have to be chopped prior to buffer2array().

Don't do two allocations for the mod_Data structure.

The log file is duped to STDOUT_FILENO and STDERR_FILENO.  No need to
keep another copy of it in out_fd all the time.  We only need it once
once in setup_log_output().

When MPD exits, it should manually free all resources in use, to allow
easy memory leak debugging.  Make the decoder thread terminate during
that.

Allow logging to syslog if log_file is configured to "syslog".

Added log_init_file() and log_init_stdout(), preparing for other
logging targets.

The logging library currently has 3 constructor functions: initLog(),
open_log_files(), setup_log_output(), called in this order.  Merged
the first two.

Declare log_threshold as GLogLevelFlags.

If the user wants the log files with a specific mode, he has to start
MPD with the correct umask.  Don't hard-code that.

This fixes a bug: when log cycling failed, MPD would not restore the
old umask.

Merged code from open_log_files() and cycle_log_files().