Refactor thread_info to remove the RefCell

[tgross35]

thread_info currently uses RefCell-based initialization. Refactor this to use OnceCell instead which is more performant and better suits the needs of one-time initialization.

This is nobody's bottleneck but OnceCell checks are a single cmp vs. RefCell<Option> needing runtime logic

[rustbot]

r? @thomcc

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[thomcc]

Thanks.

@bors r+ rollup=never

[bors]

📌 Commit 207b609 has been approved by thomcc

It is now in the queue for this repository.

[bors]

⌛ Testing commit 207b609 with merge ed33e40...

[bors]

☀️ Test successful - checks-actions
Approved by: thomcc
Pushing ed33e40 to master...

[rust-timer]

Finished benchmarking commit (ed33e40): comparison URL.

Overall result: no relevant changes - no action needed

@rustbot label: -perf-regression

Instruction count

This benchmark run did not return any relevant results for this metric.

Max RSS (memory usage)

This benchmark run did not return any relevant results for this metric.

Cycles

Results

This is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	5.0%	[4.9%, 5.0%]	2
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-	-	0

Binary size

Results

This is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-0.0%	[-0.0%, -0.0%]	1
All ❌✅ (primary)	-	-	0

Bootstrap: 631.695s -> 632.622s (0.15%)
Artifact size: 317.87 MiB -> 317.96 MiB (0.03%)