Bug 1915397 - fix unitialized scalar field in MboxCompactor. r=BenC DONTBUILD

CID: 1600522

Differential Revision: https://phabricator.services.mozilla.com/D220399

--HG--
extra : amend_source : bccd7a21c75fd27609710d718dfd1eebc8a700f2

mailnews/local/src/nsMsgBrkMBoxStore.cpp

@@ -241,6 +241,8 @@ class MboxCompactor : public nsIStoreScanListener {
       : mFolder(folder),
         mCompactListener(listener),
         mOriginalMboxFileSize(0),
+        mMsgFlags(0),
+        mNewMsgSize(0),
         mPatchXMozillaHeaders(patchXMozillaHeaders) {}
 
   /*