Use -Clinker-plugin-lto in bootstrap

[Kobzol]

An experiment discussed in https://rust-lang.zulipchat.com/#narrow/channel/131828-t-compiler/topic/rustc-codegen-utc/with/623556350, with the goal of speeding up dist CI slightly.

[Kobzol]

@bors try @rust-timer queue

[rust-bors]

💔 Test for bb7879a failed: CI. Failed jobs:

• try - dist-aarch64-linux-quick (web logs, enhanced plaintext logs)
• try - dist-x86_64-linux-quick (web logs, enhanced plaintext logs)

[Kobzol]

@bors try

[rust-bors]

☀️ Try build successful (CI)
Build commit: f5dac37 (f5dac377a296b4767c165047690532fd1f5cc4f7)
Base parent: 574ff7d (574ff7d98bd6d037e5236a8453029173b32631fd)

[rust-timer]

Finished benchmarking commit (f5dac37): comparison URL.

Overall result: ❌✅ regressions and improvements - no action needed

Benchmarking means the PR may be perf-sensitive. Consider adding rollup=never if this change is not fit for rolling up.

@rustbot label: -S-waiting-on-perf -perf-regression

Instruction count

Our most reliable metric. Used to determine the overall result above. However, even this metric can be noisy.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	0.3%	[0.3%, 0.3%]	2
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-0.3%	[-0.3%, -0.3%]	2
All ❌✅ (primary)	-	-	0

Max RSS (memory usage)

Results (secondary 2.4%)

A less reliable metric. May be of interest, but not used to determine the overall result above.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	4.0%	[2.3%, 5.1%]	4
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-4.1%	[-4.1%, -4.1%]	1
All ❌✅ (primary)	-	-	0

Cycles

Results (primary -2.9%, secondary -0.3%)

A less reliable metric. May be of interest, but not used to determine the overall result above.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	14.0%	[8.1%, 25.8%]	3
Improvements ✅ (primary)	-2.9%	[-2.9%, -2.9%]	1
Improvements ✅ (secondary)	-5.1%	[-7.5%, -3.0%]	9
All ❌✅ (primary)	-2.9%	[-2.9%, -2.9%]	1

Binary size

This perf run didn't have relevant results for this metric.

Bootstrap: 496.664s -> 495.964s (-0.14%)
Artifact size: 406.89 MiB -> 407.09 MiB (0.05%)