coverity#708545 Uninitialized scalar field

Change-Id: I97efb9c1f3bb6554dfded43129a13f93d1cdd4be

tools/source/generic/bigint.cxx

@@ -570,7 +570,9 @@ BigInt::BigInt( sal_uInt32 nValue )
     else
     {
         bIsBig = false;
+        bIsNeg = false;
         nVal   = nValue;
+        nLen   = 0;
     }
 }