configure.ac: Add --enable-64-bit-words option

The old 32 bit words the default which can be overridded with this
configure option.

configure.ac

@@ -269,6 +269,15 @@ AC_ARG_ENABLE(werror,
 AC_ARG_ENABLE(stack-smash-protection,
 	AC_HELP_STRING([--enable-stack-smash-protection], [Enable GNU GCC stack smash protection]))
 
+AC_ARG_ENABLE(64-bit-words,
+	AC_HELP_STRING([--enable-64-bit-words], [Set FLAC__BYTES_PER_WORD to 8 (4 is the default)]))
+if test "x$enable_64_bit_words" = xyes ; then
+	AC_DEFINE_UNQUOTED([ENABLE_64_BIT_WORDS],1,[Set FLAC__BYTES_PER_WORD to 8 (4 is the default)])
+else
+	AC_DEFINE_UNQUOTED([ENABLE_64_BIT_WORDS],0)
+	fi
+AC_SUBST(ENABLE_64_BIT_WORDS)
+
 AC_ARG_ENABLE(valgrind-testing,
 AC_HELP_STRING([--enable-valgrind-testing], [Run all tests inside Valgrind]),
 [case "${enableval}" in

src/libFLAC/bitreader.c

@@ -49,7 +49,7 @@
 /* WATCHOUT: there are a few places where the code will not work unless brword is >= 32 bits wide */
 /*           also, some sections currently only have fast versions for 4 or 8 bytes per word */
 
-#if 1
+#if (ENABLE_64_BIT_WORDS == 0)
 
 typedef FLAC__uint32 brword;
 #define FLAC__BYTES_PER_WORD 4		/* sizeof brword */

src/libFLAC/bitwriter.c

@@ -48,7 +48,7 @@
 /* WATCHOUT: if you change this you must also change the following #defines down to SWAP_BE_WORD_TO_HOST below to match */
 /* WATCHOUT: there are a few places where the code will not work unless bwword is >= 32 bits wide */
 
-#if 1
+#if (ENABLE_64_BIT_WORDS == 0)
 
 typedef FLAC__uint32 bwword;
 #define FLAC__BYTES_PER_WORD 4		/* sizeof bwword */

src/test_libFLAC/bitwriter.c

@@ -33,7 +33,7 @@
  * the definition here to get at the internals.  Make sure this is kept up
  * to date with what is in ../libFLAC/bitwriter.c
  */
-#if 1
+#if (ENABLE_64_BIT_WORDS == 0)
 
 typedef FLAC__uint32 bwword;
 #define FLAC__BYTES_PER_WORD 4