Minor packaging cleanup

As mentioned in Debian BTS#945646, python 2 is being removed from Debian. This patch set ports a single, relatively simple script to python 3.

This patch addresses a lintian error regarding libcrypto_utils.so not linking libc. It does this with a lintian override, but also adds an explicity -Wl,-z,defs check to guard against accidentally failing to link all required libraries. I've tested this rebuilt module by booting a phone with fastboot, and using adb.

It also fixes the spelling of simg2simg in the package description.

Per my email to the BTS Jan 5, 2020, I've also tested the patch to simg_dump.py.