Fixed posix_spawnp usage (#16336)

src/process/posix/SDL_posixprocess.c

@@ -355,10 +355,8 @@ bool SDL_SYS_CreateProcessWithProperties(SDL_Process *process, SDL_PropertiesID
         case 0:
             // Detach from the terminal and launch the process
             setsid();
-            if (posix_spawnp(&data->pid, args[0], &fa, &attr, args, envp) != 0) {
-                _exit(errno);
-            }
-            _exit(0);
+            int result = posix_spawnp(&data->pid, args[0], &fa, &attr, args, envp);
+            _exit(result);
 
         default:
             if (waitpid(pid, &status, 0) < 0) {
@@ -372,8 +370,9 @@ bool SDL_SYS_CreateProcessWithProperties(SDL_Process *process, SDL_PropertiesID
             break;
         }
     } else {
-        if (posix_spawnp(&data->pid, args[0], &fa, &attr, args, envp) != 0) {
-            SDL_SetError("posix_spawn() failed: %s", strerror(errno));
+        int result = posix_spawnp(&data->pid, args[0], &fa, &attr, args, envp);
+        if (result != 0) {
+            SDL_SetError("posix_spawn() failed: %s", strerror(result));
             goto posix_spawn_fail_all;
         }
     }