github-ci: Master CI improvements re: Travis CI

github-ci: Master CI improvements re: Travis CI

This is a squashed commit of the following items:

github-ci: Fedora 32 builder with asan enabled

Also enables -Wshadow and rust-strict to cover those cases
from Travis.

Redmine issue:
https://redmine.openinfosecfoundation.org/issues/3868

(cherry picked from commit c91b43a3fdf2e072f354c2082247b20804629b67)

github-ci: ubuntu 20.04 build without nss/nspr

Adds a test that builds and tests Suricata without nss/nspr
to replace the similar test on Travis-CI.

Redmine issue:
https://redmine.openinfosecfoundation.org/issues/3869

(cherry picked from commit 7ea2187f9191225cdab40d8fde49439c94824023)

github-ci: Ubuntu 20.4 build with -NDEBUG

To cover Travis-CI test that builds with -NDEBUG.

Redmine issue:
https://redmine.openinfosecfoundation.org/issues/3869

(cherry picked from commit 0dc6434e61e6a37c38f0ccda59ae56d714a2b268)

github-ci: enable debug on Fedora 32 build

(cherry picked from commit db0be04988d238d89c1a27cdc35dfcd1b0ab4a14)

github-ci: update debian 9 test to use known Rust version

Choose Rust 1.39.0 as a known version of Rust that we build against
to see in CI if we build with this version, but fail with latest.

This is to cover a similar test from Travis CI.

(cherry picked from commit 94ac702159f263bad6e480498ed894d8cb91be4a)

github-ci: add test build without jansson

This is to cover a test from Travis CI where we make sure
that ./configure fails if libjansson is not available.

(cherry picked from commit a35756e140bc48302cea55399a0cb09158d9cbc7)

github-ci: apply default CFLAGS to all builds

(cherry picked from commit b3a55a4cd5b291c66a79b6a56a49571152e5ba7f)

github-ci: Fixups for parity with master

rust: add doc target to build rust docs

Uses "cargo doc --no-deps" to build the documentation just for
our Suricata package. Without --no-deps, documentation will be
build for all our dependencies as well.

The generated documentation will end up in target/doc as HTML.

(cherry picked from commit 7ca24041b666bc9c9190a3c78d03d66b6ebebac6)

github-ci: CentOS 6 is EOL

(cherry picked from commit 3ea33f5e4756c9bdb5b9f0535b1acf46e392202b)