…ault

Also, add opcache to default extensions since it significantly
increases PHP's performance and is by default enabled on Debian based
distributions. Not having it enabled by default results in a puzzling
performance loss for anyone attempting to migrate from Debian/Ubuntu
to NixOS who is unaware of this. Therefore, enable it by default. /talyz

…aren't used

This moves yet more extensions from the base build to
phpPackages.ext. Some of the extensions are a bit quirky and need
patching for this to work, most notably mysqlnd and opcache.

Two new parameters are introduced for mkExtension - internalDeps and
postPhpize. internalDeps is used to specify which other internal
extensions the current extension depends on, in order to provide them
at build time. postPhpize is for when patches and quirks need to be
applied after running phpize.

Patch notes:

- For opcache, older versions of PHP have a bug where header files are
  included in the wrong order.

- For mysqlnd, the config.h is never included, so we include it in the
  main header file, mysqlnd.h. Also, the configure script doesn't add
  the necessary library link flags, so we add them to the variable
  configure should have added them to.

The tests for many of the extensions run just fine, for some a small
portion fail. This runs the tests by default and disables the tests
extensions with any failing tests.

A slight rewrite of buildEnv which:

1. Makes buildEnv recursively add itself to its output, so that it can
   be accessed from any php derivation.

2. Orders the extension text strings according to their internalDeps
   attribute - dependencies have to be put before dependants in the
   php.ini or they will fail to load due to missing symbols.

This means php packages can now refer to other php packages by looking
them up in the php.packages attribute and gets rid of the internal
recursive set previously defined in php-packages.nix. This also means
that in applications where previously both the php package and the
corresponding version of the phpPackages package set had to be
specified, the php package will now suffice.

This also adds the phpWithExtensions parameter to the
php-packages.nix, which can be used by extensions that need a fully
featured PHP executable.

Make mkExtension put headers in the dev output and use them, instead of
a different part of the current source tree, when referring to another
extension by using internalDeps.

This means external extensions can be built against the internal ones.

Introduce the internalDeps attribute used by mkExtension, to refer to
internal php extensions built by mkExtension.

… a flag

Make sure all the extensions are loaded first, then read the custom
config where possible.

Fix extensions that were broken by the extension refactoring and
remove pthreads and pinba, which had asserts which broke evaluation,
were in need of refactoring and of dubious value.

This test checks that we evaluate PHP properly and that certain
extensions are actually loaded.

…butes

So now we have only packages for human interaction in php.packages and
only extensions in php.extensions. With this php.packages.exts have
been merged into the same attribute set as all the other extensions to
make it flat and nice.

The nextcloud module have been updated to reflect this change as well
as the documentation.

This provides a means to build a PHP package based on a list of
extensions from another.

For example, to generate a package with all default extensions
enabled, except opcache, but with ImageMagick:

php.withExtensions (e:
  (lib.filter (e: e != php.extensions.opcache) php.enabledExtensions)
  ++ [ e.imagick ])

PHP: Make the default package more sane [v3]