Change naming convention of object files to follow what Base Julia does

[gbaraldi]

Fixes #738

I'm not sure why this makes macos broken, but given that the fix is simple I'm also not going to dig into it.

The tests don't all pass because fooifier isn't there for macos, @staticfloat would need to rebuild it or we just switch to another random artifact.

It also prints a bunch of

ld: warning: no platform load command found in '/var/folders/fs/z9fkqy2n5djg4663njw_c20m0000gn/T/jl_4TmZI5eNyL-o.a[2](text#0.o)', assuming: macOS
ld: warning: no platform load command found in '/var/folders/fs/z9fkqy2n5djg4663njw_c20m0000gn/T/jl_4TmZI5eNyL-o.a[3](text#1.o)', assuming: macOS
ld: warning: no platform load command found in '/var/folders/fs/z9fkqy2n5djg4663njw_c20m0000gn/T/jl_4TmZI5eNyL-o.a[4](text#2.o)', assuming: macOS
ld: warning: no platform load command found in '/var/folders/fs/z9fkqy2n5djg4663njw_c20m0000gn/T/jl_4TmZI5eNyL-o.a[5](text#3.o)', assuming: macOS
ld: warning: no platform load command found in '/var/folders/fs/z9fkqy2n5djg4663njw_c20m0000gn/T/jl_4TmZI5eNyL-o.a[6](text#4.o)', assuming: macOS

Which was fixed by JuliaLang/julia#51830 but that didn't get backported into 1.10.

[staticfloat]

For the fooifier stuff, probably best to just use a JLL like HelloWorldC_jll or something like that. We don't want to actually add it as a dependency though, we want to embed the Artifacts.toml file directly, to continue testing the artifacts handling, so do something like just download an Artifacts.toml file from a JLL and embed it directly into the test suite here.

[sloede]

I am really happy to see this issue fixed, thanks a lot, though I truly am baffled by how this fix is supposed to work 😬

Just two small remarks:

1. The ld warning seems to appear only on macOS platforms, right? Can we maybe add an @info statement on macOS systems immediately before or after, informing the user that if said warning appears, it is ok to ignore?
2. The rationale for using the -o.a extension is very subtle. It would be imho great to add a small comment that explains why this is necessary (and/or links to this PR).

[DilumAluthge]

@gbaraldi What's the status here? We just need to fix the fooifier problem?