[PATCH v2] ld.so: Check for new cache format first and enhance corruption check

[Florian Weimer]

* Florian Weimer via Libc-alpha:

> Now that ldconfig defaults to the new format (only), check for it
> first.  Also apply the corruption check added in commit 2954daf00bb4d
> ("Add more checks for valid ld.so.cache file (bug 18093)") to the
> new-format-only case.

I've pushed this, as the feedback for v1 already looked like approval.

Thanks,
Florian