Fix for a "table is full" bug in multi-table updates (Bug #7788)

mysys/my_handler.c:
  Fix for a bug in multi table updates, when offset of one table is 
  5 bytes or more. This occured because in that case binary(5) indexed
  column is space packed, so it was hit by this bug in the function
  for binary comparison.
  Bug #7788

mysys/my_handler.c

@@ -57,7 +57,7 @@ static int compare_bin(uchar *a, uint a_length, uchar *b, uint b_length,
       /* put shorter key in a */
       a_length= b_length;
       a= b;
-      swap= -1;					/* swap sign of result */
+      swap= -1 ^ 1;					/* swap sign of result */
     }
     for (end= a + a_length-length; a < end ; a++)
     {