Build Failure With libxml2-2.12.3

### Provide environment information

```bash
When trying to install version 7.4.30 on my Manjaro it gives the following error:

/tmp/tmp.VNdgogunqW/php-src-php-7.4.0/ext/libxml/libxml.c:990:49: error: passing argument 2 of ‘xmlSetStructuredErrorFunc’ from incompatible pointer type [-Wincompatible-pointer-types]
990 | xmlSetStructuredErrorFunc(NULL, php_libxml_structured_error_handler);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
| |
| void (*)(void *, xmlError *) {aka void (*)(void *, struct _xmlError *)}
```

### To Reproduce

asdf install php 7.4.0

### Describe the Bug

To reproduce the error, just run the installation command.

### Expected Behaviour

I want you to correctly install the PHP version.

Run `asdf install php 7.4.0` on Manjaro with libxml2-2.12.3 and capture the failure. Start with `ext/libxml/libxml.c` at the reported `xmlSetStructuredErrorFunc` call, then inspect the surrounding build path. Done means PHP 7.4.0 installs successfully in the reported environment.

Written by the indexing model from the issue text.