From clang-13:
hw/audio/adlib.c:189:18: error: variable 'net' set but not used \
    [-Werror,-Wunused-but-set-variable]
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
 static void adlib_callback (void *opaque, int free)
 {
     AdlibState *s = opaque;
-    int samples, net = 0, to_play, written;
+    int samples, to_play, written;
 
     samples = free >> SHIFT;
     if (!(s->active && s->enabled) || !samples) {
         written = write_audio (s, samples);
 
         if (written) {
-            net += written;
             samples -= written;
             s->pos = (s->pos + written) % s->samples;
         }