find: make InodeMatcher & LinksMatcher unix-only

[cakebaker]

This PR is a refactoring that makes the implementations of InodeMatcher and LinksMatcher unix-only. And moves the error handling for other platforms to where we handle -inum and -links.

The refactoring is done to get rid of two "field x is never read" warnings on Windows (see, for example, https://github.com/uutils/findutils/actions/runs/9271426702/job/25506758917#step:6:185)

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 60.51%. Comparing base (5b19ea2) to head (cd0e119).

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #393      +/-   ##
==========================================
+ Coverage   60.48%   60.51%   +0.02%     
==========================================
  Files          32       32              
  Lines        4069     4067       -2     
  Branches      895      893       -2     
==========================================
  Hits         2461     2461              
  Misses       1254     1254              
+ Partials      354      352       -2     

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[github-actions]

GNU testsuite comparison:

Run GNU findutils tests: GNU tests summary = TOTAL: 718 / PASS: 433 / FAIL: 282 / ERROR: 2
Run GNU findutils tests: Changes from main: PASS +0 / FAIL +0 / ERROR +0 / SKIP +0 
Run BFS tests: Changes from main: PASS +0 / SKIP +0 / FAIL +0
Run BFS tests: BFS tests summary = TOTAL: 288 / PASS: 182 / SKIP: 1 / FAIL: 105

[sylvestre]

@hanbings maybe we should display it only when here are changes.
it will be too noisy otherwise

[hanbings]

@hanbings maybe we should display it only when here are changes. it will be too noisy otherwise

OK, I'll open a new PR to work on it.