Manage valgrind instrumentation with profiling cli

[GuillaumeLagrange]

• Add a small c library that enables and disables valgrind instrumentation at dynamic link through constructor and destructor attributes (which are supported by both gcc and clang)
• Embed the library into the exec-harness binary
• Load this library using LD_PRELOAD, after writing it to disk at runtime

[codspeed-hq]

Merging this PR will not alter performance

✅ 4 untouched benchmarks

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_{Comparing cod-1739-manage-valgrind-instrumentation-with-profiling-cli (a90b8ff) with main (ce63cb0)}

[Copilot]

Pull request overview

This PR adds support for managing Valgrind instrumentation in exec-harness by introducing a C preload library that enables/disables callgrind instrumentation. The library is compiled during build, embedded into the binary, and loaded via LD_PRELOAD when running benchmarks in simulation mode.

Changes:

• Added C preload library for Valgrind instrumentation control
• Implemented build script to compile and embed the preload library
• Added simulation/instrumentation mode support with valgrind-based execution

Reviewed changes

Copilot reviewed 8 out of 10 changed files in this pull request and generated 10 comments.

Show a summary per file

File	Description
crates/exec-harness/build.rs	New build script that compiles the C preload library and exports constants
crates/exec-harness/preload/codspeed_preload.c	New C library that manages Valgrind instrumentation via constructor/destructor
crates/exec-harness/src/constants.rs	New module defining shared constants between Rust and C code
crates/exec-harness/src/analysis.rs	Added perform_with_valgrind function that extracts and uses the preload library
crates/exec-harness/src/lib.rs	Enabled simulation mode with "instrumentation" alias
crates/exec-harness/src/uri.rs	Added command field and print_executing helper method
crates/exec-harness/src/walltime/mod.rs	Added logging for benchmark execution
crates/exec-harness/Cargo.toml	Updated codspeed to 4.2.0, added build dependencies
.gitignore	Added compile_commands.json and .cache

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