fix unchecked length in stb_vorbis that could crash on corrupt/invalid files
static void neighbors(uint16 *x, int n, int *plow, int *phigh)
{
   int low = -1;
   int high = 65536;
   int i;
   for (i=0; i < n; ++i) {
      if (x[i] > low  && x[i] < x[n]) { *plow  = i; low = x[i]; }
      if (x[i] < high && x[i] > x[n]) { *phigh = i; high = x[i]; }
   }
}

static void neighbors(uint16 *x, int n, int *plow, int *phigh)
{
   int low = -1;
   int high = 65536;
   int i;
   for (i=0; i < n; ++i) {
      if (x[i] > low  && x[i] < x[n]) { *plow  = i; low = x[i]; }
      if (x[i] < high && x[i] > x[n]) { *phigh = i; high = x[i]; }
   }
}
