missing return value check in sb_socket()

All the other seccomp_rule_add calls check their return values. One doesn't.

It probably should conform.

--- a/src/common/sandbox.c
+++ b/src/common/sandbox.c
@@ -547,6 +547,8 @@ sb_socket(scmp_filter_ctx ctx, sandbox_cfg_t *filter)
       SCMP_CMP(0, SCMP_CMP_EQ, PF_UNIX),
       SCMP_CMP_MASKED(1, SOCK_CLOEXEC|SOCK_NONBLOCK, SOCK_STREAM),
       SCMP_CMP(2, SCMP_CMP_EQ, 0));
+  if (rc)
+    return rc;
 
   rc = seccomp_rule_add_3(ctx, SCMP_ACT_ALLOW, SCMP_SYS(socket),
       SCMP_CMP(0, SCMP_CMP_EQ, PF_NETLINK),