Despite the good intentions, 4f965557 makes Debian contributors who
follows gimp-web-devel instructions to download more deps than needed
and makes unclear what are the crossroad deps. Let's fix it.
This makes crossroad and msys2 scripts clone without the "_" prefix, which
will improve quality of life of most contributors that just clone them.
Just for consistency, also remove the "_" prefix from other pices of code.
It's perfectly reasonable that someone can misunderstand the scripts info in
gimp-web-devel and try to run them not from git root but from their dirs. So,
let's add that possibility as a fallback (a pretty natural one by the way).
Also, change the error message to direct contributors to gimp-web-devel.
The ARTIFACTS_SUFFIX is being dropped on building scripts because:
1) This will make possible to further simplify Installer scripts in other commit
2) There is no script that uses multi-arch _build/_install at same time on CI
However, there are two use cases: to build Debian and flatpak; and, on Win,
to build on CLANGARM64 and CLANG64 (?). But probably they are pretty niche.
I suppose that people who build on Debian (or other dev-oriented distro)
willn't want to mantain deps in two sys prefixes (pkg and GNOME runtime)
+ two gimp prefixes (out of sandbox and sandbox) due to huge storage use.
Why someone would want to build with emulation on Win ARM64 I don't know.
Anyway, people that know how to do this stuff probably can change the .sh.
3) When building locally, the contributor doesn't need to know the arch at all.
Indeed, without this suffix, the scripts are inline with gimp-web-devel and
prevent some first-sight confusion when reading them that I've seen on IRC.
4) These arch suffixes can be understood as '_install-*' being distributable
which is not true. So, without this suffix we could make more clear
what is a package (when GitLab fix the glob bug in 'expose_as' someday).
---
Despite .gitlab-ci.yml not being a script, it needed to be touched too
because cross scripts depends on Debian jobs due to gimp-data MR.
The numbering is now inline with actual the order of jobs on CI
to make easier to understand what the numbers represent.
To understand why bundling is number 2 see: d09a2a6f and 2dc6f411
The storing of Windows scripts was changed to make easier to
call them, to better convey that they work outside CI and
to be consistent with other build/ subdirectories.