dest.c: Don't look for user config in cupsGetNamedDest as root

[zdohnal]

We were still looking into ~/.cups/lpoptions as root in the function, which IMHO is not expected.

[michaelrsweet]

I guess. cupsSetDests never writes there so it should just be a no-op already, but it doesn't hurt to add a check. For readability, maybe just put the #ifdef around the whole if, e.g.:

#ifdef _WIN32
  if (cg->userconfig)
#else 
  if (cg->userconfig && getuid())
#endif // _WIN32

[zdohnal]

@michaelrsweet thx, I have applied that - additionally I found another place where we should add the check - see the updated PR.

What I experience there is Selinux AVC when an application which runs as a root (f.e. cups-browsed) uses libcups dest API and attempts to access /root/.cups/lpoptions, which is not set in policy as allowed. And since we want to access /etc/cups/lpoptions as root, it makes more sense to fix libcups than adding new selinux policy rule.

[michaelrsweet]

OK, looks good to me.