fix vrc7 issue #235, update state.c (#245)

* vrc7: Add sound save states

* Try to fix some save state issues

try to fix big-endian related save problems

* vrc7: fix crash in some cases when loading states

src/fceu-endian.c

@@ -31,7 +31,10 @@ void FlipByteOrder(uint8 *src, uint32 count)
    uint8 *start = src;
    uint8 *end = src + count - 1;
 
-   while(start < end)
+   if ((count & 1) || !count)
+      return;     /* This shouldn't happen. */
+
+   while (count--)
    {
       uint8 tmp;