Full posix_spawn support #167
Description
The standard library uses posix_spawn where possible, so this is necessary for spawning processes from rust nowadays. Some of these functions already have a stub implementation, but many are missing and those that have a stub implementation will need to actually be implemented.
- posix_spawn
- posix_spawnattr_destroy
- posix_spawnattr_getflags
- posix_spawnattr_getpgroup
- posix_spawnattr_getsigdefault
- posix_spawnattr_getsigmask
- posix_spawnattr_init
- posix_spawnattr_setflags
- posix_spawnattr_setpgroup
- posix_spawnattr_setsigdefault
- posix_spawnattr_setsigmask
- posix_spawn_file_actions_addchdir
- posix_spawn_file_actions_addchdir_np
- posix_spawn_file_actions_addclose
- posix_spawn_file_actions_adddup2
- posix_spawn_file_actions_addopen
- posix_spawn_file_actions_destroy
- posix_spawn_file_actions_init
- posix_spawnp