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!

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