core: parse '@default' seccomp group permissively

We are about to add system calls (rseq()) not available on old
libseccomp/old kernels, and hence we need to be permissive when parsing
our definitions.

src/core/load-fragment.c

@@ -2695,7 +2695,9 @@ int config_parse_syscall_filter(
                         c->syscall_whitelist = true;
 
                         /* Accept default syscalls if we are on a whitelist */
-                        r = seccomp_parse_syscall_filter("@default", -1, c->syscall_filter, SECCOMP_PARSE_WHITELIST);
+                        r = seccomp_parse_syscall_filter(
+                                        "@default", -1, c->syscall_filter,
+                                        SECCOMP_PARSE_PERMISSIVE|SECCOMP_PARSE_WHITELIST);
                         if (r < 0)
                                 return r;
                 }