[Xcb] [PATCH] check if allocated image is NULL _before_ first derefence

[Barton C Massey]

In message <838225.87221.qm at web59915.mail.ac4.yahoo.com> you wrote:
> Also, I've always considered "mixing declaration and code"
> to be a feature not a bad habit. Of course, in some code
> bases it's necessary to support old compilers but the
> xcb-util code seems to be mixing declaration and code
> already, right? Or is it per block and not per function?

Declaring at the point of definition is great style, but it
still really isn't a widely supported C feature, and we're
trying not to be gcc-only, so if you find it somewhere
please fix it.  The same with // comments.

    Bart