Python master doesn't build on macOS Tiger anymore:

http://buildbot.python.org/all/#/builders/30/builds/581

./Modules/posixmodule.c:251:19: error: spawn.h: No such file or directory
./Modules/posixmodule.c: In function ‘os_posix_spawn_impl’:
./Modules/posixmodule.c:5174: error: ‘posix_spawn_file_actions_t’ undeclared (first use in this function)
./Modules/posixmodule.c:5174: error: (Each undeclared identifier is reported only once
./Modules/posixmodule.c:5174: error: for each function it appears in.)
./Modules/posixmodule.c:5174: error: ‘file_actionsp’ undeclared (first use in this function)
./Modules/posixmodule.c:5176: error: parse error before ‘_file_actions’
./Modules/posixmodule.c:5177: warning: implicit declaration of function ‘posix_spawn_file_actions_init’
./Modules/posixmodule.c:5177: error: ‘_file_actions’ undeclared (first use in this function)
./Modules/posixmodule.c:5232: warning: implicit declaration of function ‘posix_spawn_file_actions_addopen’
./Modules/posixmodule.c:5245: warning: implicit declaration of function ‘posix_spawn_file_actions_addclose’
./Modules/posixmodule.c:5262: warning: implicit declaration of function ‘posix_spawn_file_actions_adddup2’
./Modules/posixmodule.c:5274: warning: implicit declaration of function ‘posix_spawn’
make: *** [Modules/posixmodule.o] Error 1

See also bpo-32705: "Current Android does not have posix_spawn" (now fixed). In PR 5413 of this bpo, it was also asked if "#define HAVE_POSIX_SPAWN 1" of posixmodule.c makes sence since there is already a configure check for posix_spawn()?

https://github.com/python/cpython/pull/5413#issuecomment-361183294