Typo made it impossible to disable ALSA 0.9 plugin compilation.

git-svn-id: http://svn.xiph.org/trunk/ao@2320 0101bb08-14d6-0310-b084-bc0e0c8e3800

configure.in

@@ -183,7 +183,7 @@ dnl Check for ALSA 0.9.x
 AC_ARG_ENABLE(alsa09, [  --enable-alsa09           include alsa 0.9 output plugin ],
 [ BUILD_ALSA09="$enableval" ],[ BUILD_ALSA09="yes" ])
 
-if test "$BUILD_ALSA" = "yes"; then
+if test "$BUILD_ALSA09" = "yes"; then
    AC_CHECK_LIB(asound, snd_pcm_open, have_alsa09=yes, have_alsa09=no)
    AC_CHECK_HEADER(sys/asoundlib.h, , have_alsa09=no)
    AM_CONDITIONAL(HAVE_ALSA09,test "x$have_alsa09" = xyes)