namespace: move protect_{home|system} into NamespaceInfo

it's not entirely clear what shall be passed via parameter and what via
struct, but these two definitely fit well with the other protect_xyz
fields, hence let's move them over.

We probably should move a lot more more fields into the structure
actuall (most? all even?).

src/test/test-namespace.c

@@ -163,8 +163,6 @@ static void test_protect_kernel_logs(void) {
                                     NULL,
                                     NULL,
                                     NULL,
-                                    PROTECT_HOME_NO,
-                                    PROTECT_SYSTEM_NO,
                                     0,
                                     NULL,
                                     0,

src/test/test-ns.c

@@ -76,8 +76,6 @@ int main(int argc, char *argv[]) {
                             tmp_dir,
                             var_tmp_dir,
                             NULL,
-                            PROTECT_HOME_NO,
-                            PROTECT_SYSTEM_NO,
                             0,
                             NULL,
                             0,