[zstd] Reuse the ZSTD_CCtx more often with small data.

lib/compress/zstd_compress_internal.h

@@ -314,6 +314,7 @@ MEM_STATIC void ZSTD_storeSeq(seqStore_t* seqStorePtr, size_t litLength, const v
                pos, (U32)litLength, (U32)mlBase+MINMATCH, (U32)offsetCode);
     }
 #endif
+    assert((size_t)(seqStorePtr->sequences - seqStorePtr->sequencesStart) < seqStorePtr->maxNbSeq);
     /* copy Literals */
     assert(seqStorePtr->lit + litLength <= seqStorePtr->litStart + 128 KB);
     ZSTD_wildcopy(seqStorePtr->lit, literals, litLength);