[php-src] Issue #21960: php-8.5.6 build failure with gcc16

Issue: https://github.com/php/php-src/issues/21960
Author: BlackIkeEagle

### Description

When building PHP-8.5.6 in an Arch Linux chroot I get some musttail / setjmp issue

```
core/gcc                      16.1.1+r12+g301eb08fa2c5-1
```

Build log: https://cdn.artifacts.gitlab-static.net/6b/83/6b836ad53e8e13e9156d898efc4f1b42a09baa9a6eab898c0297f16fd244c7a1/2026_05_06/14233067314/16535162422/job.log?response-content-type=text%2Fplain%3B%20charset%3Dutf-8&response-content-disposition=inline&Expires=1778057439&KeyName=gprd-artifacts-cdn&Signature=ykqrv-T0kgNHk1DYmyXcjQC9hS0=


Currently I "fixed" the building with the following patch:

```
diff --git a/Zend/zend_portability.h b/Zend/zend_portability.h
index 6546ebfb5b7..8cbaaa19b37 100644
--- a/Zend/zend_portability.h
+++ b/Zend/zend_portability.h
@@ -336,14 +336,6 @@ char *alloca();
 # define ZEND_PRESERVE_NONE __attribute__((preserve_none))
 #endif
 
-
-#if !defined(__apple_build_version__) || (defined(__apple_build_version__) && __apple_build_version__ >= 17000404)
-# if __has_attribute(musttail)
-#  define HAVE_MUSTTAIL
-#  define ZEND_MUSTTAIL __attribute__((musttail))
-# endif
-#endif
-
 #if (defined(__GNUC__) && __GNUC__ >= 3 && !defined(__INTEL_COMPILER) && !defined(__APPLE__) && !defined(__hpux) && !defined(_AIX) && !defined(__osf__)) || __has_attribute(noreturn)
 # define HAVE_NORETURN
 # define ZEND_NORETURN __attribute__((noreturn))
```

### PHP Version

```plain
Build failure
```

### Operating System

Arch Linux