Apply LTO config to rustdoc

[Kobzol]

Before, the LTO configuration from config.toml was not applied to rustdoc. This provides a small perf. and binary size win for doc builds.

Since this is configured with Cargo profiles and not rustflags, it should not break tool build cache (#131155). I tried to run x test miri, x test rustdoc and x test miri and nothing was rebuilt.

r? @onur-ozkan

[onur-ozkan]

That's a good imrovement. You may want to add a change entry for this :)

[Kobzol]

Ok, I'll do that. Let's also double check that the perf. win applies on this PR.

@bors try @rust-timer queue

[bors]

⌛ Trying commit 2a25286 with merge 5f13723...

[bors]

☀️ Try build successful - checks-actions
Build commit: 5f13723 (5f13723e9423dd9c2e1962e48d07a29942d2daea)

[rust-timer]

Finished benchmarking commit (5f13723): comparison URL.

Overall result: ✅ improvements - no action needed

Benchmarking this pull request likely means that it is perf-sensitive, so we're automatically marking it as not fit for rolling up. While you can manually mark this PR as fit for rollup, we strongly recommend not doing so since this PR may lead to changes in compiler perf.

@bors rollup=never
@rustbot label: -S-waiting-on-perf -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
Improvements ✅ (primary)	-0.3%	[-0.6%, -0.2%]	9
Improvements ✅ (secondary)	-0.2%	[-0.3%, -0.2%]	3
All ❌✅ (primary)	-0.3%	[-0.6%, -0.2%]	9

Max RSS (memory usage)

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

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: 764.328s -> 765.487s (0.15%)
Artifact size: 326.09 MiB -> 325.96 MiB (-0.04%)

[Kobzol]

Updated the change tracker.

@rustbot ready