rustc-dev-guide subtree update

[Kobzol]

This PR performs the first update of rustc-dev-guide code from its repository.

r? @BoxyUwU

[BoxyUwU]

@bors r+ rollup=never

[bors]

📌 Commit 515d7eb has been approved by BoxyUwU

It is now in the queue for this repository.

[bors]

⌛ Testing commit 515d7eb with merge b3b368a...

[bors]

☀️ Test successful - checks-actions
Approved by: BoxyUwU
Pushing b3b368a to master...

[rust-timer]

Finished benchmarking commit (b3b368a): comparison URL.

Overall result: ❌ regressions - no action needed

@rustbot label: -perf-regression

Instruction count

This is the most reliable metric that we have; it was used to determine the overall result at the top of this comment. However, even this metric can sometimes exhibit noise.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	0.4%	[0.4%, 0.4%]	1
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-	-	0

Max RSS (memory usage)

Results (primary 2.3%, secondary -3.0%)

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)	2.3%	[2.0%, 2.8%]	8
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-3.0%	[-3.0%, -3.0%]	1
All ❌✅ (primary)	2.3%	[2.0%, 2.8%]	8

Cycles

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

Binary size

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

Bootstrap: 762.79s -> 763.545s (0.10%)
Artifact size: 325.66 MiB -> 325.56 MiB (-0.03%)