Improve platform-specific crypto filenames

[dagood]

Follows up on #2157 (comment)

AI review is totally right IMO, darwin_darwin is redundant ("stuttering") for no good reason:

 create mode 100644 src/crypto/internal/backend/fips140/cng_windows.go
 create mode 100644 src/crypto/internal/backend/fips140/darwin_darwin.go
 create mode 100644 src/crypto/internal/backend/fips140/openssl_linux.go

Not only that, darwin_darwin.go also doesn't include the name of the backend like the cng and openssl files do in their names. And one step further: these files are serving the same purpose, so they should share a prefix to be easier to find and more readable.

Updated patches to change names to:

 create mode 100644 src/crypto/internal/backend/fips140/systemfips_darwin.go
 create mode 100644 src/crypto/internal/backend/fips140/systemfips_linux.go
 create mode 100644 src/crypto/internal/backend/fips140/systemfips_windows.go

 create mode 100644 src/crypto/internal/backend/backend_darwin.go
 create mode 100644 src/crypto/internal/backend/backend_linux.go
 create mode 100644 src/crypto/internal/backend/backend_windows.go

 create mode 100644 src/crypto/rsa/rsa_darwin.go

(Can use git go-patch review to confirm that these are just renames.)

[github-actions]

Patch Consistency Review: ✅ APPROVED

This PR successfully improves the platform-specific filename conventions across the patches. The changes are consistent and follow the repository guidelines.

Summary of Changes

The PR renames platform-specific files to use clearer, more consistent naming conventions:

In 0003-Implement-crypto-internal-backend.patch:

• darwin_darwin.go → backend_darwin.go
• openssl_linux.go → backend_linux.go
• cng_windows.go → backend_windows.go
• fips140/darwin_darwin.go → fips140/systemfips_darwin.go
• fips140/openssl_linux.go → fips140/systemfips_linux.go
• fips140/cng_windows.go → fips140/systemfips_windows.go

In 0004-Use-crypto-backends.patch:

• rsa/darwin_darwin.go → rsa/rsa_darwin.go

Consistency Checks ✅

1. Filename suffix convention: All files correctly use _darwin.go, _linux.go, _windows.go suffixes to indicate platform constraints, eliminating the redundant "darwin_darwin" pattern.

2. Build tag adherence: The build tags properly follow guideline Build a Docker prereqs image for linux-amd64 longtest #5 - they specify only //go:build goexperiment.systemcrypto without duplicating the OS/arch that's already expressed in the filename suffix.

3. Unified naming: Files serving the same purpose across platforms now share consistent prefixes (backend_*, systemfips_*, rsa_*) making them easier to find and more readable.

4. No extraneous blank lines: The code maintains appropriate spacing between functions and import groups per guideline Skip tests during official builds #6.

5. Patch organization: All related platform-specific changes are grouped in the correct patches (backend implementation in 0003, crypto usage in 0004).

The renaming makes the codebase more maintainable and follows Go conventions. Great improvement! 🎉

AI generated by Patch Consistency Review Agent