php: add intl extension back to the php formula

[shivammathur]

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• As we have switched back to clang for PHP 8.5, it makes sense to keep intl extension part of the php formula. It made sense as a separate formula as it needed clang and building php with gcc had considerable performance gains, but now that we are using clang again with tailcall VM, there is no real benefit to keep it in separate formula, it causes various issues.
• Moving a single extension to a separate formula creates confusion, breaking changes and adds maintenance burden. I like the idea in https://github.com/Homebrew/homebrew-core/issues/206404, but then all PHP extensions that can be build as shared should be moved to separate formulae, instead of moving just one, and such change would be part of brew's documentation and not just a caveat.
• For the 8.5.0 release, as per the package stats around 96% of PHP installs from the core tap do not have intl, and I think many of them might have missed the caveat and not installed the php-intl package.

[shivammathur]

@cho-m What are your thoughts on this?

[LordSimal]

so does this mean php8.4 is the only minor version which would require the separate php-intl package?

If so, then the php-intl formular should be adjusted to only depend on [email protected]

[shivammathur]

@LordSimal [email protected] no longer needs a seperate formula for intl after https://github.com/Homebrew/homebrew-core/pull/255291.