Initialise mpDBManager to nullptr in the !HAVE_FEATURE_DBCONNECTIVITY case

Change-Id: Id18bafaaf8f5315a0590687d98ea97952bdf883b
Reviewed-on: https://gerrit.libreoffice.org/62624Reviewed-by: Michael Meeks <michael.meeks@collabora.com>
Tested-by: Michael Meeks <michael.meeks@collabora.com>

sw/source/core/doc/docnew.cxx

@@ -347,6 +347,8 @@ SwDoc::SwDoc()
 #if HAVE_FEATURE_DBCONNECTIVITY
     // Create DBManager
     mpDBManager = new SwDBManager(this);
+#else
+    mpDBManager = nullptr;
 #endif
 
     // create TOXTypes