fixed bug in legacy decoder v0.2, reported by Maciej Adamczyk

lib/legacy/zstd_v02.c

@@ -3155,6 +3155,7 @@ static size_t ZSTD_decodeLiteralsBlock(void* ctx,
             {
 				if (litSize > srcSize-3) return ERROR(corruption_detected);
 				memcpy(dctx->litBuffer, istart, litSize);
+				dctx->litPtr = dctx->litBuffer;
 				dctx->litBufSize = BLOCKSIZE;
 				dctx->litSize = litSize;
 				return litSize+3;