Libdatadog String interning

[r1viollet]

What does this PR do?

A brief description of the change being made with this pull request.

Motivation

What inspired you to submit this pull request? In order to motivate your point, it may be valuable to explain why this change is useful or what problem is being solved.

Additional Notes

This is the section to put technical guidance/constraints, call out potential regressions, cite sources, and in general offer some exposition on the how of the PR. This section doesn't need to be incredibly detailed, but it makes life easier for reviewers!

How to test the change?

Describe here in detail how the change can be validated. This is a great section to call out specific tests you've added or improved, or to acknowledge code sections which are particularly difficult to test.

[pr-commenter]

Benchmark results for collatz

Parameters

	Baseline	Candidate
config	baseline	candidate
profiler-version	ddprof 0.23.0+dee61e6b.93527399	ddprof 0.23.0+341431ba.94312212

Summary

Found 0 performance improvements and 0 performance regressions! Performance is the same for 1 metrics, 0 unstable metrics.

See unchanged results

scenario	Δ mean execution_time
scenario:ddprof -S bench-collatz --preset cpu_only collatz_runner.sh	same

[pr-commenter]

Benchmark results for BadBoggleSolver_run

Parameters

	Baseline	Candidate
config	baseline	candidate
profiler-version	ddprof 0.23.0+dee61e6b.93527399	ddprof 0.23.0+341431ba.94312212

Summary

Found 0 performance improvements and 0 performance regressions! Performance is the same for 1 metrics, 0 unstable metrics.

See unchanged results

scenario	Δ mean execution_time
scenario:ddprof -S bench-bad-boggle-solver BadBoggleSolver_run work 1000	same

[r1viollet]

Deploying to relenv to see what this yields