fulltest: add 11 new POSIX syscall tests and wrappers

fulltest: add 11 new POSIX syscall tests and wrappers

New tests (I1-I12):
- geteuid/getegid: verify euid/egid match uid/gid for root
- seteuid/setegid: root can change and restore euid/egid
- CLOCK_MONOTONIC: monotonic clock advances after nanosleep
- chown: change file owner
- futex: FUTEX_WAIT returns EAGAIN on mismatch, WAKE returns 0
- sigaltstack: set/query/disable alternate signal stack
- socket API: TCP socket create/bind/listen/getsockname/shutdown
- mqueue: POSIX message queue open/send/receive/close/unlink
- named semaphore: sem_open/post/wait/getvalue/close/unlink
- getrusage: query RUSAGE_SELF (non-zero fields)
- mount/umount2: mount tmpfs, create file, unmount

New syscall wrappers added to fulltest:
sys_chown, sys_futex, sys_sigaltstack, sys_socket, sys_bind,
sys_listen, sys_accept, sys_connect, sys_send, sys_recv,
sys_shutdown, sys_getsockname, sys_mq_open/close/send/receive/unlink,
sys_sem_open/close/wait/post/unlink/getvalue, sys_getrusage,
sys_sigqueue, sys_mount, sys_umount2, sys_execveat

New constants: FUTEX_WAIT/WAKE, AF_INET, SOCK_STREAM, IPPROTO_TCP,
RUSAGE_SELF, struct sockaddr_in, plus enum values for all new syscalls

Updated smoke_test.exp and test_battery.exp to track new tests.
Test results: 114/114 QEMU, 27/27 battery, 69/69 host