[patch] Fix jit-reader.h for multilib

[Joel Brobecker]

> As I said this patch may not affect much/any other distros because
>  * at least Debian does not ship jit-reader.h at all
>  * other distros may not consider GDB as a multilib package

I don't think the problem would be specific to Fedora - it is
possible that other distros might benefit from the fix as well.
The only thing that gave me pause was the relatively strange
fix, and the fact that I didn't really understand the issue,
and therefore didn't understand the fix. I don't know much
about jit-reader.h, and the impact of the fix, but I have
a feeling that it would beneficial to others and therefore should
be considered for inclusion.

-- 
Joel