vmm: add syscalls to seccomp filters for sending SIGTERM

Add lstat and getcwd to allowed seccomp filter list since they
 are called in libc::kill.

Signed-off-by: Songqian Li <sionli@tencent.com>

vmm/src/seccomp_filters.rs

@@ -688,6 +688,9 @@ fn vmm_thread_rules(
         (libc::SYS_wait4, vec![]),
         (libc::SYS_write, vec![]),
         (libc::SYS_writev, vec![]),
+        #[cfg(target_arch = "x86_64")]
+        (libc::SYS_lstat, vec![]),
+        (libc::SYS_getcwd, vec![]),
     ])
 }