libmount: map unsupported LISTMOUNT_REVERSE to ENOSYS

For testing purposes, report the missing LISTMOUNT_REVERSE as missing
in the complete listmount() function.

Signed-off-by: Karel Zak <kzak@redhat.com>

libmount/src/tab_listmount.c

@@ -100,6 +100,7 @@ static int table_init_listmount(struct libmnt_table *tb, size_t stepsiz)
 				DBG(TAB, ul_debugobj(tb, "listmount: unsuppported"));
 			if (errno == EINVAL)
 				DBG(TAB, ul_debugobj(tb, "listmount: reverse unsuppported"));
+			errno = ENOSYS;
 			return -ENOSYS;
 		}
 	}

tests/helpers/test_sysinfo.c

@@ -163,7 +163,7 @@ static int hlp_listmount_ok(void)
 #else
 	errno = ENOSYS;
 #endif
-	printf("%d\n", errno != ENOSYS);
+	printf("%d\n", !(errno == ENOSYS || errno == EINVAL));
 	return 0;
 }