Fix macOS posix_spawn_file_actions_addchdir availability handling

[arshidkv12]

#21720

[NattyNarwhal]

I think this might be able to be simplified by checking __ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__/__ENVIRONMENT_OS_VERSION_MIN_REQUIRED__ instead, since we don't need any real runtime differences, it's just a symbol name, and the old one is unlikely to go away right now even if it's deprecated. It should respect -mmacosx-version-min as well.

[arshidkv12]

Thank you

[NattyNarwhal]

Still triggers the deprecation on 26;

/Users/calvin/src/php-src/ext/standard/proc_open.c:1409:7: error: 'posix_spawn_file_actions_addchdir_np' is deprecated: first deprecated in macOS
      26.0 - posix_spawn_file_actions_addchdir(3) has replaced posix_spawn_file_actions_addchdir_np(3) [-Werror,-Wdeprecated-declarations]
 1409 |                 r = POSIX_SPAWN_FILE_ACTIONS_ADDCHDIR(&factions, cwd);
      |                     ^
/Users/calvin/src/php-src/ext/standard/proc_open.c:53:44: note: expanded from macro 'POSIX_SPAWN_FILE_ACTIONS_ADDCHDIR'
   53 |         #define POSIX_SPAWN_FILE_ACTIONS_ADDCHDIR posix_spawn_file_actions_addchdir_np
      |                                                   ^
/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/usr/include/spawn.h:182:9: note: 
      'posix_spawn_file_actions_addchdir_np' has been explicitly marked deprecated here
  182 | int     posix_spawn_file_actions_addchdir_np(posix_spawn_file_actions_t *,
      |         ^

I think you need the AvailabilityMacros.h header to use the unembellished macro names:

calvin@anika-5 php-src % echo | cc -dM -E -mmacosx-version-min=10.15 - | grep MAC_OS_X_VERSION_MIN_REQUIRED
#define __ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__ 101500
calvin@anika-5 php-src % echo "#include <AvailabilityMacros.h>" | cc -dM -E -mmacosx-version-min=10.15 - | grep MAC_OS_X_VERSION_MIN_REQUIRED
#define MAC_OS_X_VERSION_MIN_REQUIRED __ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__
#define __ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__ 101500
#define __MAC_OS_X_VERSION_MIN_REQUIRED __ENVIRONMENT_OS_VERSION_MIN_REQUIRED__

[NattyNarwhal]

Builds with -enable-werror for me on 26 (well, and -Wno-unterminated-string-initialization, but that's a lexbor thing).