vmm: seccomp: Allow clock_gettime() on the vCPU thread

If the vCPU thread calls log!() the time difference between the call
time and the boot up time is reported. On most environments and
architectures this covered by a vDSO call rather than a syscall. However
on some platforms this turns into a syscall.

Fixes: #2080

Signed-off-by: Rob Bradford <robert.bradford@intel.com>

vmm/src/seccomp_filters.rs

@@ -409,6 +409,7 @@ fn vcpu_thread_rules() -> Result<Vec<SyscallRuleSet>, Error> {
     Ok(vec![
         allow_syscall(libc::SYS_accept4),
         allow_syscall(libc::SYS_brk),
+        allow_syscall(libc::SYS_clock_gettime),
         allow_syscall(libc::SYS_clock_nanosleep),
         allow_syscall(libc::SYS_clone),
         allow_syscall(libc::SYS_close),