lkl: drop libarchive cptofs dependency

[ddiss]

Unlike fs2tar, cptofs doesn't appear to use libarchive in any way. The dependency appears to have been added by accident via commit 2030bf6 ("lkl tools: improve the build system").

[github-actions]

Test Results

 87 files   - 19   87 suites   - 19   10m 56s ⏱️ + 3m 35s
194 tests  - 12  183 ✅  - 12  11 💤 ± 0  0 ❌ ±0 
710 runs   - 80  666 ✅  - 68  44 💤  - 12  0 ❌ ±0 

Results for commit 765be37. ± Comparison against base commit 00ff347.

This pull request removes 12 tests.

net wintap ‑ cleanup_backend wintap
net wintap ‑ icmp
net wintap ‑ if_up
net wintap ‑ nd_add
net wintap ‑ nd_create
net wintap ‑ nd_ifindex
net wintap ‑ nd_remove
net wintap ‑ set_gateway
net wintap ‑ set_ipv4
net wintap ‑ sleep
…

This pull request skips 1 test.

net wintap ‑ setup_backend wintap

[ddiss]

This sees the cptofs build enabled on Windows, which fails with:

[5](https://github.com/lkl/linux/actions/runs/35874529377/job/107226902615?pr=644#step:16:1746)
cptofs.c:7:10: fatal error: argp.h: No such file or directory
    7 | #include <argp.h>