grep: -q match yields exit 0 even after a file error

[sylvestre]

GNU grep documents that with -q the exit status is 0 as soon as a line is selected, even if an error (such as a missing file) occurred. uu_grep let had_error take precedence, so 'grep -q PAT missing -' returned 2 instead of 0 when stdin matched. Give quiet+match priority in finish(); without -q, or with -q and no match, a file error still yields exit 2. Fixes the GNU testsuite 'status' test.

[github-actions]

GNU grep testsuite comparison:

Test results comparison:
  Current:   TOTAL: 128 / PASSED: 71 / FAILED: 36 / SKIPPED: 21
  Reference: TOTAL: 128 / PASSED: 70 / FAILED: 37 / SKIPPED: 21

Changes from main branch:
  TOTAL: +0
  PASSED: +1
  FAILED: -1

Test improvements (1):
  + status

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 95.90%. Comparing base (98e6bb6) to head (399d2d1).

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #11      +/-   ##
==========================================
+ Coverage   95.82%   95.90%   +0.07%     
==========================================
  Files           6        6              
  Lines        1414     1416       +2     
  Branches      140      141       +1     
==========================================
+ Hits         1355     1358       +3     
+ Misses         58       57       -1     
  Partials        1        1              

Flag	Coverage Δ
macOS_latest	96.72% <100.00%> (+0.07%)	⬆️
ubuntu_latest	96.72% <100.00%> (+0.07%)	⬆️
windows_latest	0.00% <0.00%> (ø)

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[codspeed-hq]

Merging this PR will not alter performance

✅ 10 untouched benchmarks
⏩ 17 skipped benchmarks¹

---

_{Comparing grep-quiet-exit-after-error (d0263b2) with main (b4980df)}

Footnotes

1. 17 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩

[lhecker]

Thinking about it some more, a shorter expression of the old code is had_error && !(quiet && any_match), but I'm not sure if that's any more readable.