Fix GH-22118: Compare equivalent fake closures in FCCs

[prateekbhujel]

First-class method callable syntax creates a fresh fake Closure object for each expression. Some callback comparisons were still treating Closure-backed callables by Closure object identity, so equivalent fake Closures could fail to unregister.

Update zend_fcc_equals() so regular Closure objects still compare by object identity, while fake Closures compare through their Closure method definition instead of generic object comparison. On master, SPL autoload already uses zend_fcc_equals(), so the same path is covered there too.

Fixes GH-22118.

Tests:

• PATH="/opt/homebrew/opt/bison/bin:/opt/homebrew/bin:$PATH" ./configure --disable-all --enable-cli
• PATH="/opt/homebrew/opt/bison/bin:/opt/homebrew/bin:$PATH" make -j$(sysctl -n hw.ncpu) sapi/cli/php
• sapi/cli/php run-tests.php -q -p sapi/cli/php ext/standard/tests/general_functions/gh22118.phpt ext/spl/tests/autoloading/gh22118.phpt ext/spl/tests/autoloading/gh10011.phpt ext/spl/tests/autoloading/spl_autoload_013.phpt ext/spl/tests/autoloading/spl_autoload_014.phpt ext/spl/tests/autoloading/bug75049.phpt ext/spl/tests/autoloading/spl_autoload_unregister_without_registrations.phpt ext/standard/tests/general_functions/bug66094.phpt

[Girgias]

IMO this should be fixed in zend_fcc_equals() as this same issue would crop up if trying to register and unregister an autoloader using a FCC.

[prateekbhujel]

Sorry, you’re right, this was too narrowly placed before. I moved the fake-Closure comparison into zend_fcc_equals() and reused the same helper for SPL autoload’s stored callback comparison, with a new spl_autoload_unregister() regression test for the FCC case you mentioned.

I pushed the updated branch and ran the focused tick + SPL autoload tests locally.

[Girgias]

Trampoline test and this needs to be backported to PHP 8.4 rather than 8.5 as this issue has existed for longer.

[TimWolla]

For visibility.