copy the correct version of LLVM into the stage0 sysroot

[onur-ozkan]

In some cases(see #109314), when the stage0
compiler relies on more recent version of LLVM than the beta compiler, it may not
be able to locate the correct LLVM in the sysroot. This situation typically occurs
when we upgrade LLVM version while the beta compiler continues to use an older version.

Fixes #109314

[rustbot]

r? @Mark-Simulacrum

(rustbot has picked a reviewer for you, use r? to override)

[Mark-Simulacrum]

@bors r+ rollup=iffy

I'm going to go ahead and approve but let's keep an eye out for any regressions and back out if needed.

[bors]

📌 Commit aec4b59 has been approved by Mark-Simulacrum

It is now in the queue for this repository.

[bors]

⌛ Testing commit aec4b59 with merge ebbd715...

[bors]

☀️ Test successful - checks-actions
Approved by: Mark-Simulacrum
Pushing ebbd715 to master...

[bors]

☀️ Test successful - checks-actions
Approved by: Mark-Simulacrum
Pushing ebbd715 to master...

[rust-timer]

Finished benchmarking commit (ebbd715): comparison URL.

Overall result: ❌ regressions - no action needed

@rustbot label: -perf-regression

Instruction count

This is a highly reliable metric that was used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	0.4%	[0.4%, 0.4%]	2
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-	-	0

Max RSS (memory usage)

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)	4.1%	[2.9%, 5.3%]	2
Regressions ❌ (secondary)	2.1%	[1.8%, 2.4%]	2
Improvements ✅ (primary)	-2.6%	[-2.6%, -2.6%]	1
Improvements ✅ (secondary)	-3.3%	[-3.4%, -3.2%]	2
All ❌✅ (primary)	1.9%	[-2.6%, 5.3%]	3

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: 632.481s -> 631.811s (-0.11%)