Add hash for devilutionx

[DavisNT]

The devilutionx-src.tar.xz is probably generated during DevilutionX release and its hash for a particular DevilutionX version shouldn't change over time.

This change has been tested in several full clean builds (make rk3326-cleanbuild).

[dmanlfc]

i would rather we didn't tbh. it's just extra maintenance on updates.
you'll notice many third-party packages in batocera we don't bother.
why do you think it's super necessary apart from the obvious?

[n2qz]

@DavisNT If I understand correctly, your intention here is to deal with the name of the source archive staying the same when the version changes. When that happens, a new version may not be downloaded as intended. If the hash doesn't match, Buildroot should download a new revision.

If that's the intention, a better approach (with or without the hash validation) would be to store each downloaded version in a directory containing the version number, something like this:

DEVILUTIONX_DL_DIR = $(BR2_DL_DIR)/devilutionx-$(DEVILUTIONX_VERSION)

[DavisNT]

@n2qz When the version is bumped the download URL changes, I haven't tested whether buildroot handles this correctly.

The reason I would like to add the hash is for security (in case existing releases would get maliciously modified, we would know) and stability (in the rare event something gets changed by authors, we would know).

DevilutionX is not special in any way here. I made this PR because when my build of clean master branch failed due to incorrect devilutionx hash and I asked in Discord whether the hash needs to be updated it got removed altogether.