[PATCH 3/3] PR4886: Check build-id in module_init function if able.

[Frank Ch. Eigler]

Hi, Wenji -

Excellent work.  If it passes regression tests, please check it in.
It shouldn't be hard to apply it to userspace too, if it doesn't
already just work.

Some tweaks to the various messages may be helpful later, such as to
print parts of the buildid strings for eyeballing by the user, but
otherwise it looks just fine.

- FChE