Fix:

error: use of undeclared identifier 'environ'

https://dev.gnupg.org/T7169
--- src/spawn-posix.c.orig	2024-06-19 02:33:41.000000000 -0500
+++ src/spawn-posix.c	2024-06-21 01:54:38.000000000 -0500
@@ -57,6 +57,11 @@
 
 #include "gpgrt-int.h"
 
+#ifdef __APPLE__
+# include <crt_externs.h>
+#else
+extern char **environ;
+#endif
 
 /* Definition for the gpgrt_spawn_actions_t.  Note that there is a
  * different one for Windows.  */
@@ -342,7 +347,11 @@
   _gpgrt_close_all_fds (3, act->except_fds);
 
   if (act->environ)
+#ifdef __APPLE__
+    *_NSGetEnviron() = act->environ;
+#else
     environ = act->environ;
+#endif
 
   if (act->atfork)
     act->atfork (act->atfork_arg);