Fix autostart file symlink

[lenemter]

Fixes #76

Closes #75

[Marukesu]

you could upper the minimum meson version to 0.61 and use install_symlink().

an apt show meson gives me o.61.2, so that won't be a problem for elementary.

[danirabbit]

Probably should also incorporate #75 while here?

[lenemter]

Probably should also incorporate #75 while here?

I think this PR does the exact same thing as #75 except checking is_absolute, which is false in both elementary OS and NixOS.

[lenemter]

@Marukesu with install_symlink the stable and unstable CI fail. Any idea why?

[Marukesu]

it's seems we are triggering mesonbuild/meson#10176, the fix is present in 0.61.5.

[bobby285271]

I think this PR does the exact same thing as #75 except checking is_absolute, which is false in both elementary OS and NixOS.

According to docs, when the prefix is /usr, sysconfdir defaults to /etc, I think in this case is_absolute is true, and in other case sysconfdir defaults to etc, in this case is_absolute is false... Though I expect the check is only needed when using the custom install script (yes, this PR works fine for me, though we still need #74).

[lenemter]

@bobby285271 Thanks for clarification, I added changes from #75 here.

[lenemter]

Double checked and autostart file is correctly installed.