pam-p11: Fail to build against OpenSSL 3.0

Hello,

As part of a rebuild against OpenSSL3, this package failed to build on one or
several architectures. You can find the details of the rebuild at

https://people.canonical.com/~schopin/rebuilds/openssl-3.0.0-impish.html

or for the amd64 failed build, directly at

https://launchpad.net/~schopin/+archive/ubuntu/openssl-3.0.0/+build/22099243/+files/buildlog_ubuntu-impish-amd64.pam-p11_0.3.1-1.0~ssl3ppa1.1_BUILDING.txt.gz

We're planning to transition to OpenSSL 3.0 for the 22.04 release, and consider
this issue as blocking for this transition.

You can find general migration informations at
https://www.openssl.org/docs/manmaster/man7/migration_guide.html
For your tests, you can build against libssl-dev as found in the PPA
schopin/openssl-3.0.0

The build errors are from a -Werror flag, a quick workaround would be to add
-Wno-error=deprecated-declarations to the CFLAGS, or to port the module to the newer APIs.

I didn't find any mention of OpenSSL 3.0 in the upstream repo.