coverity#984163 Uninitialized scalar field

Change-Id: I3ad2a8d22ef274a63de5c01cc74c7d46f947f861

tools/source/generic/bigint.cxx

@@ -484,6 +484,7 @@ BigInt::BigInt( const BigInt& rBigInt )
 }
 
 BigInt::BigInt( const OUString& rString )
+    : nLen(0)
 {
     bIsSet = true;
     bIsNeg = false;