avcodec/sbrdsp_fixed: fix runtime error: left shift of 1 by 31 places cannot be represented in type 'int'

Fixes: part of 1709/clusterfuzz-testcase-minimized-4513580554649600

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
(cherry picked from commit 384508b2ff)
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

libavcodec/sbrdsp_fixed.c

@@ -229,11 +229,11 @@ static void sbr_hf_gen_c(int (*X_high)[2], const int (*X_low)[2],
 static void sbr_hf_g_filt_c(int (*Y)[2], const int (*X_high)[40][2],
                           const SoftFloat *g_filt, int m_max, intptr_t ixh)
 {
-    int m, r;
+    int m;
     int64_t accu;
 
     for (m = 0; m < m_max; m++) {
-        r = 1 << (22-g_filt[m].exp);
+        int64_t r = 1LL << (22-g_filt[m].exp);
         accu = (int64_t)X_high[m][ixh][0] * ((g_filt[m].mant + 0x40)>>7);
         Y[m][0] = (int)((accu + r) >> (23-g_filt[m].exp));