[RFA] record.c - save some memory in record log.

[Hui Zhu]

>
> One way that we have used in the past that might be helpful here
> is to define the buffer at the end of the structure and without
> the pointer indirection:
>
>   struct blah
>   {
>     ...
>
>     int buffer_len;
>     gdb_byte buf[0];
>   };
>
> The allocation of the structure become a little trickier. And access
> to the buffer is a little more dangerous, which is why I don't like
> this approach much.  But it does save memory, and you can prevent
> buffer overrun by forcing access to this data through accessor
> routines...
>

Hi Joel,

But I think:
+  union
+  {
+    gdb_byte *ptr;
+    gdb_byte buf[2 * sizeof (gdb_byte *)];

Make the size of buf more clear.

Thanks,
Hui