perf(sourcemap): search lines count at parallel

[underfin]

Description

[netlify]

✅ Deploy Preview for rolldown-rs canceled.

Name	Link
🔨 Latest commit	fadfd38
🔍 Latest deploy log	https://app.netlify.com/sites/rolldown-rs/deploys/6614fbc635fdb60008c53af0

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 80.45%. Comparing base (9bb01eb) to head (fef2e8d).
Report is 1 commits behind head on main.

❗ Current head fef2e8d differs from pull request most recent head fadfd38. Consider uploading reports for the commit fadfd38 to get more accurate results

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #806      +/-   ##
==========================================
- Coverage   80.50%   80.45%   -0.05%     
==========================================
  Files         130      131       +1     
  Lines        6611     6627      +16     
==========================================
+ Hits         5322     5332      +10     
- Misses       1289     1295       +6     

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[codspeed-hq]

CodSpeed Performance Report

Merging #806 will not alter performance

_{Comparing make-lines-count-parallel (fadfd38) with main (9bb01eb)}

Summary

✅ 6 untouched benchmarks