Fix an overflow with freq=4096 in the SSE4 decoder.

Specifically, the SIMD decoder handles this case, but the tidyup code
at the end for any remainder of < 32 bytes to go didn't.

Triggered by the follow example:

    perl -e 'print "\0"x0xff0,"AAABAA\0"'|./tests/rans4x16pr -t -o5 -c 0x0201

Author: jkbonfield

htscodecs/rANS_static32x16pr_sse4.c

@@ -1414,8 +1414,10 @@ unsigned char *rans_uncompress_O1_32x16_sse4(unsigned char *in,
             uint32_t S = s3[l[z]][m];
             unsigned char c = S & 0xff;
             out[i4[z]++] = c;
-            R[z] = (S>>(TF_SHIFT_O1+8)) * (R[z]>>TF_SHIFT_O1) +
-                ((S>>8) & ((1u<<TF_SHIFT_O1)-1));
+            int f = (S>>(TF_SHIFT_O1+8));
+            if (f == 0)
+                f = 4096;
+            R[z] = f * (R[z]>>TF_SHIFT_O1) + ((S>>8) & ((1u<<TF_SHIFT_O1)-1));
             RansDecRenormSafe(&R[z], &ptr, ptr_end);
             l[z] = c;
         }