rustc_monomorphize cleanups

[nnethercote]

Just some small improvements I found while looking over this code.

r? @wesleywiser

[rustbot]

These commits modify the Cargo.lock file. Unintentional changes to Cargo.lock can be introduced when switching branches and rebasing PRs.

If this was unintentional then you should revert the changes before this PR is merged.
Otherwise, you can ignore this comment.

[wesleywiser]

@bors r+

[bors]

📌 Commit a145b49 has been approved by wesleywiser

It is now in the queue for this repository.

[bors]

⌛ Testing commit a145b49 with merge 5cee4f3...

[bors]

☀️ Test successful - checks-actions
Approved by: wesleywiser
Pushing 5cee4f3 to master...

[rust-timer]

Finished benchmarking commit (5cee4f3): 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)

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

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

Binary size

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

Bootstrap: 629.691s -> 630.247s (0.09%)
Artifact size: 304.02 MiB -> 304.06 MiB (0.01%)