Fix error code being divided by 256 in testRelease script

[arifthpe]

Remove an instance of a command status code being divided by 256 in util/buildRelease/testRelease.

I think this was likely intended to be modded to ensure the status code returned is in the typical 0-255 range. But even that may not be necessary since we just shouldn't be returning an out of range error code from whatever other script of ours this invokes anyways.

[reviewer info placeholder]

[bradcray]

It's not entirely clear to me why anything would need to be done with the error code rather than just printing it out. Is it to you? That said, what you have here is no worse than what we had (and is arguably strictly better), so I'm OK with proceeding with it.

[arifthpe]

This mod ensures that the status code is in the usual range [0,256) . I'm not sure if that range limitation comes from POSIX or Linux or bash or something else.

I'm pretty sure an out of range error code will just get modded like this by the invoking shell anyways. Not to mention we probably wouldn't have an out of range code returned by whatever other script of ours this invokes. I guess we might as well not do the mod and find out.

[bradcray]

Works for me!