Document unstable linker flags in the unstable book

[lqd]

This PR:

• removes the unstable linker flavors from the stable documentation
• documents the unstable -C linker-flavor values in the unstable book (including the ones previously described as stable)
• documents the unstable -C link-self-contained components in the unstable book

I don't know if these have some common reviewers, but if not r? @petrochenkov as the most knowledgeable person in this area. Please feel free to reassign, I know that you are quite busy.

[petrochenkov]

r=me with #119024 (comment) addressed.
@rustbot author

[lqd]

@bors r=petrochenkov

[bors]

📌 Commit 3006e62 has been approved by petrochenkov

It is now in the queue for this repository.

[bors]

⌛ Testing commit 3006e62 with merge 2a76340...

[bors]

☀️ Test successful - checks-actions
Approved by: petrochenkov
Pushing 2a76340 to master...

[rust-timer]

Finished benchmarking commit (2a76340): 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)

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)	0.5%	[0.5%, 0.5%]	1
Regressions ❌ (secondary)	1.3%	[1.3%, 1.3%]	1
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	0.5%	[0.5%, 0.5%]	1

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)	0.8%	[0.8%, 0.8%]	2
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	0.8%	[0.8%, 0.8%]	2

Binary size

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

Bootstrap: 673.256s -> 673.958s (0.10%)
Artifact size: 312.47 MiB -> 312.41 MiB (-0.02%)