Invalid output when the number of output is above 1 and using effects

[KKQ-KKQ]

The following is the example.
The 2nd and the 3rd output should be silent but actually it sounds.

I added a PR #1243.

<effect>
bus=fx1 type=fverb reverb_type=mid_hall reverb_dry=80 reverb_wet=20 reverb_input=40 reverb_size=0 reverb_predelay=0.01 reverb_tone=50 reverb_damp=50 fx1tomix=100
<global>
effect1=100
<region>sample=*sine
ampeg_attack=0.02 ampeg_release=0.1
output=0
<region>sample=*saw
ampeg_attack=0.02 ampeg_release=0.1
output=3