Allow adding external v1 sst file with no global seqno support

Summary:
This is a follow up fix for https://github.com/facebook/rocksdb/pull/1783. After it, we should be able to ingest external v1 sst files with no global seqno field.
Closes https://github.com/facebook/rocksdb/pull/1874

Differential Revision: D4576194

Pulled By: IslamAbdelRahman

fbshipit-source-id: 5b34a3e

db/external_sst_file_ingestion_job.cc

@@ -309,6 +309,7 @@ Status ExternalSstFileIngestionJob::GetIngestedFileInfo(
   } else if (file_to_ingest->version == 1) {
     // SST file V1 should not have global seqno field
     assert(seqno_iter == uprops.end());
+    file_to_ingest->original_seqno = 0;
     if (ingestion_options_.allow_blocking_flush ||
             ingestion_options_.allow_global_seqno) {
       return Status::InvalidArgument(