Inline zerocopy layout helpers

[joshlf]

Motivation

• Encourage the compiler to inline small, hot helpers used during layout computation to improve performance and reduce call overhead in const/inline-heavy code paths.

Description

• Add #[inline(always)] to SizeInfo::try_to_nonzero_elem_size in zerocopy/src/layout.rs.
• Add #[inline(always)] to padding_needed_for in zerocopy/src/util/mod.rs.
• Add #[inline(always)] to max and min helpers for NonZeroUsize in zerocopy/src/util/mod.rs.
• Applied changes to the zerocopy/src/ files (the requested rust/Makefile hunk was not present in this repository so it was not applied).

Testing

• Ran CARGO_ZEROCOPY_AUTO_INSTALL_TOOLCHAIN=1 ./cargo.sh +stable check --tests --features __internal_use_only_features_that_work_on_stable, which completed successfully.
• Ran git diff --check, which reported no issues.
• Invoked the repository githooks/pre-push which produced warnings about missing tools and interactive toolchain installation prompts, so it did not fully complete in this environment.

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Codex Task

[jswrenn]

This should use the CFG introduced in #3139.

[joshlf]

This should use the CFG introduced in #3139.

Done.