Uses var (otherwise not used) as parameter to open file in CFFileUtilities

[valeriyvan]

No description provided.

[spevans]

@swift-ci please test

[spevans]

@swift-ci please test

[valeriyvan]

ping

[valeriyvan]

ping

[millenomi]

cc @niw This is the CF dual of your last patch — should it be 0666?

[niw]

Actually, probably get mode by stat(2) for existing path is unnecessary at least on POSIX system, because mode (oflag) is used only when it is creating a new file by O_CREAT.
Therefore, the original code works as expected (but has unused mode,) also this patch works as expected.

I think it is preferred to not have unused mode for sure, so I think this change is reasonable.