Many years ago, FAAD had a serious ABI bug: the NeAACDecInit()
prototype in its header declared the "samplerate" parameter to be
"unsigned long *", but internally, the function assumed it was
"uint32_t *" instead.  On 32 bit machines, that was no difference, but
on 64 bit, this left one portion of the return value uninitialized;
and worse, on big-endian, the wrong word was filled.  This bug had to
be worked around in MPD (commit 9c4e97a6).

A few months later, the bug was fixed in the FAAD CVS in commit 1.117
on file libfaad/decoder.c; the commit message was:

 "Use public headers internally to prevent duplicate declarations"

The commit message was too brief at best; the problem was not
duplicate declarations, but a prototype mismatch.  No mention of the
bug fix in the ChangeLog.

The MPD project never learned about this bug fix, and so MPD would
always pass a "uin32_t *" dressed up as a "unsigned long *".  Nearly 6
years later, it's about time to fix this second ABI problem.  Let's
kill the workaround!

Many years ago, FAAD had a serious ABI bug: the NeAACDecInit()
prototype in its header declared the "samplerate" parameter to be
"unsigned long *", but internally, the function assumed it was
"uint32_t *" instead.  On 32 bit machines, that was no difference, but
on 64 bit, this left one portion of the return value uninitialized;
and worse, on big-endian, the wrong word was filled.  This bug had to
be worked around in MPD (commit 9c4e97a6).

A few months later, the bug was fixed in the FAAD CVS in commit 1.117
on file libfaad/decoder.c; the commit message was:

 "Use public headers internally to prevent duplicate declarations"

The commit message was too brief at best; the problem was not
duplicate declarations, but a prototype mismatch.  No mention of the
bug fix in the ChangeLog.

The MPD project never learned about this bug fix, and so MPD would
always pass a "uin32_t *" dressed up as a "unsigned long *".  Nearly 6
years later, it's about time to fix this second ABI problem.  Let's
kill the workaround!

Abort if --enable-libmpdclient or --enable-upnp are used with
--disable-database, instead of ignoring the mismatch silently.

Not necessary anymore, because we enable this flag unconditionally
now.

This change adds two configuration options:

  --with-eventloop=[glib|internal|auto]
  --with-pollmethod=[epoll|auto]

First allows switching between GLib event loop and internal one.
Second chooses backend to use for internal event loop.
Conditional compilation symbols are changed accordingly.
Additional helper macro MPD_OPTIONAL_FUNC_NODEF is added as well.

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.

Drop support for the old faacDec* API.

Fixes build errors on systems without libfaad, when --disable-aac was
not specified.

Some of these are not implemented properly and never worked.  And the
others are not useful; you can easily set environment variables
instead.

The underlying library has been obsolete for many years.

Rationale: vanilla libid3tag does not have any pkg-config stuff
and fails to detect because symbols from libz are not found.

Needed by ax_append_link_flags.m4.

Produce a smaller binary by removing all unused functions.

We'll add some C++11 code soon.

Use standard scripts instead of MPD's custom implementation.

Don't use MPC_CFLAGS, MPD_LIBS.

Add M4 function MPD_AUTO_PKG_LIB for pkg-config with AC_CHECK_LIB
fallback.

Use "printf" instead.

Fixes autotools warnings.

Add optional third value to results() to allow for non "yes" answers which are
considered positive.

This commit adds a new pretty print menu, we've (far) outgrown the old
menu which because hard to traverse.

Use MPD_AUTO_RESULT().  Don't force libwrap by default.

Append $FAAD_LIBS to $LIBS when detecting libmp4ff.  $FAAD_LIBS may
contain an important -L flag.

The M4 function AM_PATH_LAME (m4/lame.m4) defined a configure flag
named "--disable-lametest".  This is redundant with configure.ac's
--disable-lame-encoder, and specifying both options may break the
build.  Since AM_PATH_LAME is only called when the encoder plugin is
enabled, we can safely remove that --disable-lametest option.

This function checks whether a prerequisite for a feature was found.

When MPD_AUTO_DISABLED prints a fatal error message, include the
feature name.  This might be an important piece of information for the
user, just in case the preceding line doesn't tell him.

In the MPD_AUTO_DISABLED() function, I forgot to check for "explicitly
disabled".