cr_bsd_visible(): Style fix: Explicitly test for non-zero return codes

[olce]

Summary

MFC after: 1 week

[kib]

jhb@ prefers such code to be written as

error = XXX();
if (error != 0)
   return (error);

[emaste]

jhb@ prefers such code to be written as

IMO that is indeed clearer.

[olce]

In D43335#987861, @emaste wrote:

jhb@ prefers such code to be written as

IMO that is indeed clearer.

For me it's a minor point, but I prefer to write things like:

if ((error = XXX) != 0)

when that fits on a single line, because I find C too verbose on this occasion: It cannot express very concisely to return from the current function with a given value if it is non-zero, without using macros. I wish we could settle on a "global", well-known macro to do exactly that.

Now, if you all prefer a separate line, of course I'll adopt that convention.

I will adapt the code above to this end at commit time.