[PATCH] Configure: call "make clean" before rebuild of libatomic.

[Piotr Sikora]

Hey Maxim,

> Which problem this patch tries to solve?  As far as I see,
> libatomic properly rebuilds itself based on config.status, and an
> extra "make clean" shouldn't be needed.

While not a problem per se, it the library wouldn't be rebuild if CC
changed... But the change is mostly just to keep it in sync with rest
of the 3rd-party libraries, which nginx always rebuilds from scratch.

Best regards,
Piotr Sikora