test-tool/BlockEraseReserved: skip unless iSCSI

This test performs PDU manipulation so should only be run against iSCSI
devices.

Signed-off-by: David Disseldorp <ddiss@suse.de>

test-tool/test_sanitize_block_erase_reserved.c

@@ -56,6 +56,13 @@ void test_sanitize_block_erase_reserved(void)
 
         CHECK_FOR_SANITIZE;
         CHECK_FOR_DATALOSS;
+        if (sd->iscsi_ctx == NULL) {
+                const char *err = "[SKIPPED] This test is "
+                        "only supported for iSCSI backends";
+                logging(LOG_NORMAL, "%s", err);
+                CU_PASS(err);
+                return;
+        }
 
         local_iscsi_queue_pdu = my_iscsi_queue_pdu;