Add AGL's "beer mug" PEM file as another test input

AGL has a history of pointing out the idiosynchronies/laxness of the
openssl PEM parser in amusing ways.  If we want this functionality to
stay present, we should test that it works.

Reviewed-by: Rich Salz <rsalz@openssl.org>
Reviewed-by: Richard Levitte <levitte@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/2756)