[PHP 8.6] switch the default from NTS to ZTS

[henderkes]

Hello php-docker team,

I'm currently in the process of creating a RFC to deprecate building the NTS flavour for PHP 8.6 and removing NTS entirely in PHP 9.0. It appears that all maintainers I've been talking to are generally in favour to save on CI and source maintenance.

@TimWolla suggested I raise this here and see if you're willing to switch the defaults to ZTS already (with a -nts option available, like there is currently -zts).

Happy to answer all and any questions you have.

[tianon]

I have to admit that the reason we have a ZTS variant is not just because it's non-default, but also because our understanding is that it's been somewhat unreliable historically.

For example, there's a lot of good historical discussion in #742 -- wouldn't going "ZTS-only" mean we have to simply remove the Apache variants entirely?

[henderkes]

I'm not sure about more Apache variants - the worker/threaded one requires a ZTS build and doesn't work under NTS. The prefork one the SAPIs (cli/cgi/fpm/embed and co) all work with both.

So I think you don't have to remove anything. If/when php 9.0 removes NTS entirely, the -nts image would disappear.