introduce zzip_plugin_off_t() and mark the sizeof(off_t) in every plu… #63

All 94 tests pass, 135 skipped in 4m 17s

    41 files ±0     41 suites ±0 4m 17s ⏱️ +14s
  229 tests ±0     94 ✔️ ±0   135 💤 ±0 0 ❌ ±0
9 389 runs ±0 3 854 ✔️ ±0 5 535 💤 ±0 0 ❌ ±0

Results for commit bf3e2d6. ± Comparison against earlier commit ebc6e3b.