fixed memory leaks and almost all undefined behaviour

lib/compress/zstd_compress.c

@@ -2764,7 +2764,7 @@ ZSTD_buildSequencesStatistics(
     const BYTE* const ofCodeTable = seqStorePtr->ofCode;
     const BYTE* const llCodeTable = seqStorePtr->llCode;
     const BYTE* const mlCodeTable = seqStorePtr->mlCode;
-    ZSTD_symbolEncodingTypeStats_t stats;
+    ZSTD_symbolEncodingTypeStats_t stats = {};
 
     stats.lastCountSize = 0;
     /* convert length/distances into codes */

lib/decompress/zstd_decompress.c

@@ -723,7 +723,7 @@ static size_t ZSTD_decodeFrameHeader(ZSTD_DCtx* dctx, const void* src, size_t he
 
 static ZSTD_frameSizeInfo ZSTD_errorFrameSizeInfo(size_t ret)
 {
-    ZSTD_frameSizeInfo frameSizeInfo;
+    ZSTD_frameSizeInfo frameSizeInfo = {};
     frameSizeInfo.compressedSize = ret;
     frameSizeInfo.decompressedBound = ZSTD_CONTENTSIZE_ERROR;
     return frameSizeInfo;