avcodec/ra144: Fix runtime error: signed integer overflow: 11184810 * 404 cannot be represented in type 'int'

Fixes: 1884/clusterfuzz-testcase-minimized-4637425835966464

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

libavcodec/ra144.c

@@ -1701,7 +1701,7 @@ void ff_subblock_synthesis(RA144Context *ractx, const int16_t *lpc_coefs,
     if (cba_idx) {
         cba_idx += BLOCKSIZE/2 - 1;
         ff_copy_and_dup(ractx->buffer_a, ractx->adapt_cb, cba_idx);
-        m[0] = (ff_irms(&ractx->adsp, ractx->buffer_a) * gval) >> 12;
+        m[0] = (ff_irms(&ractx->adsp, ractx->buffer_a) * (unsigned)gval) >> 12;
     } else {
         m[0] = 0;
     }