fix: warmup being sampled by perf

[not-matthias]

No description provided.

[Copilot]

Pull Request Overview

This PR adds conditional measurement control for CodSpeed wall-time instrumentation based on whether benchmark warmup has completed. The intent is to exclude warmup iterations from measurements.

• Added IsWarmupDone() getter method to BenchmarkRunner class
• Modified CodSpeed measurement logic to only start/stop measurements after warmup completion

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
google_benchmark/src/benchmark_runner.h	Added IsWarmupDone() public getter to expose warmup completion state
google_benchmark/src/benchmark.cc	Modified CODSPEED_WALLTIME measurement to conditionally start/stop based on warmup state

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[codspeed-hq]

CodSpeed Performance Report

Merging #32 will degrade performances by 17.54%

_{Comparing cod-1589-codspeed-cpp-fix-warmup-being-sampled-by-perf (1cac95e) with cod-1575-codspeed-cpp-support-custom-benchmark-name (a34fdd1)}

Summary

⚡ 4 improvements
❌ 4 regressions
✅ 192 untouched

⚠️ Please fix the performance issues or acknowledge them on CodSpeed.

Benchmarks breakdown

	Mode	Benchmark	BASE	HEAD	Change
❌	Simulation	BM_sleep_100ms	396.7 µs	473.3 µs	-16.19%
❌	Simulation	BM_sleep_10ms	38.8 µs	47 µs	-17.54%
❌	Simulation	BM_sleep_1ms	3.7 µs	4.4 µs	-15.43%
❌	Simulation	BM_sleep_50ms	198.6 µs	235.3 µs	-15.58%
⚡	Simulation	BM_sleep_100ms	771.1 µs	478.1 µs	+61.29%
⚡	Simulation	BM_sleep_10ms	76 µs	47.7 µs	+59.25%
⚡	Simulation	BM_sleep_1ms	6.8 µs	4.4 µs	+55.15%
⚡	Simulation	BM_sleep_50ms	385.5 µs	237.8 µs	+62.12%