eac3dec: replace undefined 1<<31 with INT32_MIN in noise generation

libavcodec/eac3dec.c

@@ -140,7 +140,7 @@ void ff_eac3_apply_spectral_extension(AC3DecodeContext *s)
            each band. */
         bin = s->spx_src_start_freq;
         for (bnd = 0; bnd < s->num_spx_bands; bnd++) {
-            float nscale = s->spx_noise_blend[ch][bnd] * rms_energy[bnd] * (1.0f/(1<<31));
+            float nscale = s->spx_noise_blend[ch][bnd] * rms_energy[bnd] * (1.0f / INT32_MIN);
             float sscale = s->spx_signal_blend[ch][bnd];
             for (i = 0; i < s->spx_band_sizes[bnd]; i++) {
                 float noise  = nscale * (int32_t)av_lfg_get(&s->dith_state);