decoder/faad: remove workaround for ancient libfaad2 ABI bug

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!

NEWS

@@ -1,5 +1,6 @@
 ver 0.19.2 (not yet released)
 * decoder
+  - faad: remove workaround for ancient libfaad2 ABI bug
   - ffmpeg: recognize MIME type audio/aacp
 * output
   - fix memory leak after filter initialization error

m4/faad.m4

@@ -62,36 +62,7 @@ int main() {
 	CPPFLAGS=$oldcppflags
 fi
 
-if test x$enable_aac = xyes; then
-	oldcflags=$CFLAGS
-	oldlibs=$LIBS
-	oldcppflags=$CPPFLAGS
-	CFLAGS="$CFLAGS $FAAD_CFLAGS -Werror"
-	LIBS="$LIBS $FAAD_LIBS"
-	CPPFLAGS=$CFLAGS
-
-	AC_MSG_CHECKING(for broken libfaad headers)
-	AC_COMPILE_IFELSE([AC_LANG_SOURCE([
-#include <faad.h>
-#include <stddef.h>
-#include <stdint.h>
-
-int main() {
-	unsigned char channels;
-	uint32_t sample_rate;
-
-	NeAACDecInit2(NULL, NULL, 0, &sample_rate, &channels);
-	return 0;
-}
-	])],
-		[AC_MSG_RESULT(correct)],
-		[AC_MSG_RESULT(broken);
-		AC_DEFINE(HAVE_FAAD_LONG, 1, [Define if faad.h uses the broken "unsigned long" pointers])])
-
-	CFLAGS=$oldcflags
-	LIBS=$oldlibs
-	CPPFLAGS=$oldcppflags
-else
+if test x$enable_aac = xno; then
 	FAAD_LIBS=""
 	FAAD_CFLAGS=""
 fi

src/decoder/plugins/FaadDecoderPlugin.cxx

@@ -255,20 +255,12 @@ faad_decoder_init(NeAACDecHandle decoder, DecoderBuffer &buffer,
 	}
 
 	uint8_t channels;
-	uint32_t sample_rate;
-#ifdef HAVE_FAAD_LONG
-	/* neaacdec.h declares all arguments as "unsigned long", but
-	   internally expects uint32_t pointers.  To avoid gcc
-	   warnings, use this workaround. */
-	unsigned long *sample_rate_p = (unsigned long *)(void *)&sample_rate;
-#else
-	uint32_t *sample_rate_p = &sample_rate;
-#endif
+	unsigned long sample_rate;
 	long nbytes = NeAACDecInit(decoder,
 				   /* deconst hack, libfaad requires this */
 				   const_cast<unsigned char *>(data.data),
 				   data.size,
-				   sample_rate_p, &channels);
+				   &sample_rate, &channels);
 	if (nbytes < 0) {
 		error.Set(faad_decoder_domain, "Not an AAC stream");
 		return false;

src/decoder/plugins/Mp4v2DecoderPlugin.cxx

@@ -39,15 +39,7 @@ static MP4TrackId
 mp4_get_aac_track(MP4FileHandle handle, NeAACDecHandle decoder,
 		  AudioFormat &audio_format, Error &error)
 {
-	uint32_t sample_rate;
-#ifdef HAVE_FAAD_LONG
-	/* neaacdec.h declares all arguments as "unsigned long", but
-	   internally expects uint32_t pointers.  To avoid gcc
-	   warnings, use this workaround. */
-	unsigned long *sample_rate_r = (unsigned long*)&sample_rate;
-#else
-	uint32_t *sample_rate_r = sample_rate;
-#endif
+	unsigned long sample_rate;
 
 	const MP4TrackId tracks = MP4GetNumberOfTracks(handle);
 
@@ -80,7 +72,7 @@ mp4_get_aac_track(MP4FileHandle handle, NeAACDecHandle decoder,
 
 		uint8_t channels;
 		int32_t nbytes = NeAACDecInit(decoder, buff, buff_size,
-				       sample_rate_r, &channels);
+					      &sample_rate, &channels);
 
 		free(buff);