ext/pcntl: following up php#15921 rework SYS_pidfd_open configure detection. (php#18931)

Author: devnexen

ext/pcntl/config.m4

@@ -13,7 +13,6 @@ if test "$PHP_PCNTL" != "no"; then
     forkx
     getcpuid
     getpriority
-    pidfd_open
     pset_bind
     pthread_set_qos_class_self_np
     rfork
@@ -48,6 +47,9 @@ if test "$PHP_PCNTL" != "no"; then
   AC_CHECK_DECLS([SYS_waitid],,,
     [#include <sys/syscall.h>])
 
+  AC_CHECK_DECLS([SYS_pidfd_open],,,
+    [#include <sys/syscall.h>])
+
   dnl if unsupported, -1 means automatically ENOSYS in this context
   AC_CACHE_CHECK([if sched_getcpu is supported], [php_cv_func_sched_getcpu],
   [AC_RUN_IFELSE([AC_LANG_SOURCE([

ext/pcntl/pcntl.c

@@ -125,18 +125,20 @@ typedef psetid_t cpu_set_t;
 #include <pthread/qos.h>
 #endif
 
-#if defined(__linux__) && defined(HAVE_DECL_SYS_WAITID) && HAVE_DECL_SYS_WAITID == 1 && defined(HAVE_SYSCALL)
-#define HAVE_LINUX_RAW_SYSCALL_WAITID 1
+#if defined(__linux__) && defined(HAVE_SYSCALL)
+#  include <sys/syscall.h>
+#  if defined(HAVE_DECL_SYS_WAITID) && HAVE_DECL_SYS_WAITID == 1
+#    define HAVE_LINUX_RAW_SYSCALL_WAITID 1
+#  endif
+#  if defined(HAVE_DECL_SYS_PIDFD_OPEN) && HAVE_DECL_SYS_PIDFD_OPEN == 1
+#    define HAVE_LINUX_RAW_SYSCALL_PIDFD_OPEN 1
+#  endif
 #endif
 
 #if defined(HAVE_LINUX_RAW_SYSCALL_WAITID)
 #include <unistd.h>
 #endif
 
-#if defined(HAVE_PIDFD_OPEN) || defined(HAVE_LINUX_RAW_SYSCALL_WAITID)
-#include <sys/syscall.h>
-#endif
-
 #ifdef HAVE_FORKX
 #include <sys/fork.h>
 #endif
@@ -1607,7 +1609,7 @@ PHP_FUNCTION(pcntl_forkx)
 #endif
 /* }}} */
 
-#ifdef HAVE_PIDFD_OPEN
+#ifdef HAVE_LINUX_RAW_SYSCALL_PIDFD_OPEN
 // The `pidfd_open` syscall is available since 5.3
 // and `setns` since 3.0.
 PHP_FUNCTION(pcntl_setns)