Cleanup old shims and cccfg flags

[Bo98]

• Remove apr-1-config shim. It was for system apr-1-config and that was removed from I think macOS 10.12.
• Remove a cccfg that was for apr-1-config.
• Replace ant shim with one that only tries non-system executables as /usr/bin/ant was removed in OS X 10.9. Maybe we can remove it entirely or move it to be cross-OS but I took the cautious approach in this PR.
• Remove o cccfg as it is now unconditionally set on macOS and we only read it in ldflags_mac in the shim anyway. The effect it activated remains always activated on macOS.
• Move some append_to_cccfg to determine_cccfg to be more consistent and a bit clearer
• Deprecate ENV.no_fixup_chains
  • For the superenv, it has been set by default for some time so having an API to set it is pointless. It also was a confusing API as it wouldn't actually add anything to LDFLAGS most of the time.
    • The underlying effect remains activated by default as before.
  • For the stdenv, it behaved inconsistently with how the superenv equivalent worked.
• Deprecate ENV.no_weak_imports
  • Nothing seems to use it anymore and it doesn't make sense to special-case given you could just add it to LDFLAGS if you need it.
  • Deprecating the above two ENV functions means that there will be no longer be any macOS-specific public ENV API extensions. Everything else is available on both macOS and Linux.
• Move ENV.[...]_support? methods to be private. Hopefully nothing used these as I don't think they were intended to be public API?
• Fix a few comments.

[Copilot]

Pull request overview

This PR cleans up legacy macOS superenv shims/cccfg behavior and refactors macOS ENV configuration to remove obsolete flags and tighten API surface.

Changes:

• Remove the apr-1-config shim and the associated a cccfg flag.
• Make -oso_prefix behavior unconditional (subject to existing configure/debug-symbol guards) and replace the ant shim to avoid relying on /usr/bin/ant.
• Move macOS superenv cccfg setup into determine_cccfg, and make ENV.*_support? helpers private; add deprecation notes for macOS-specific ENV APIs.

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
Library/Homebrew/shims/super/cc	Makes -oso_prefix application independent of the o cccfg flag.
Library/Homebrew/shims/mac/super/apr-1-config	Removes the legacy apr-1-config shim entirely.
Library/Homebrew/shims/mac/super/ant	Updates shim to exec only non-system ant binaries via shared shim utilities.
Library/Homebrew/extend/os/mac/extend/ENV/super.rb	Refactors cccfg determination and broadens Sonoma iconv configure workaround.
Library/Homebrew/extend/os/mac/extend/ENV/std.rb	Adds notes about deprecating macOS-specific ENV helpers in stdenv.
Library/Homebrew/extend/os/mac/extend/ENV/shared.rb	Makes *_support? helper methods private.

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[MikeMcQuaid]

Lovely cleanup, thanks @Bo98!