posix_spawn is not available on Android devices. While this commit is not necessary for cross-compiling, it is required when building on-device since there posix_spawn is found somehow. This produces following errors: ./spawn.h:514:17: error: use of undeclared identifier 'POSIX_SPAWN_RESETIDS' [(((POSIX_SPAWN_RESETIDS | POSIX_SPAWN_SETPGROUP