Adding syscall to seccomp sandbox.

src/sandbox/seccomp.rs

@@ -54,6 +54,7 @@ pub fn init() -> Result<()> {
     ctx.allow_syscall(Syscall::sched_yield)?;
     ctx.allow_syscall(Syscall::setsockopt)?;
     ctx.allow_syscall(Syscall::madvise)?;
+    ctx.allow_syscall(Syscall::rt_sigaction)?;
     #[cfg(target_arch = "x86")]
     ctx.allow_syscall(Syscall::time)?;
     ctx.allow_syscall(Syscall::clock_gettime)?;