nfs-ganesha: init at 3.3

gensio: 2.0.5 -> 2.1.3

ser2net: 4.1.8 -> 4.2.0

To specify distributed build-machines, `nix.distributedBuilds` must be
set to `true` now[1].

[1] 67b6e56

Moving just one patch forward to fix importing store-paths from
`hydra-queue-runner`[1]. The other patches[2] require a newer
`pkgs.nixUnstable` and can't be used currently due to this.

[1] NixOS/nixpkgs#93945 (comment)
[2] NixOS/hydra@77c33c1...4b58130

From the description of CVE-2020-15117:

> In Synergy before version 1.12.0, a Synergy server can be crashed by
> receiving a kMsgHelloBack packet with a client name length set to
> 0xffffffff (4294967295) if the servers memory is less than 4 GB. It
> was verified that this issue does not cause a crash through the
> exception handler if the available memory of the Server is more than
> 4GB.

While I personally would consider this a pretty low-priority issue since
Synergy usually is only used in local environment, it's nevertheless
better to patch known issues.

Since the fix is part of version 1.12, which doesn't have a stable
release yet, I'm including the fix as a patch cherry-picked from the
upstream commit.

I originally had the CVE number as a comment prior to the fetchpatch
call in question, but since @mweinelt mentioned that https://broken.sh/
uses the patch file name[1] to match whether the software in question
has been patched, I've removed my initial comment as it would be
redundant.

[1]: https://github.com/andir/nix-vulnerability-scanner/blob/fb63998885462/src/report/nix_patches.rs#L83-L95

Signed-off-by: aszlig <aszlig@nix.build>
Fixes: NixOS/nixpkgs#94007

synergy: Add patch to fix CVE-2020-15117

lowdown: init at 0.7.2

https://diffoscope.org/news/diffoscope-154-released/

Clean up, switch to Meson, remove unused test dependencies, fix license.

https://gitlab.gnome.org/GNOME/meld/-/blob/3.21.0/NEWS