QPR-11322 port commit 1f8729 from luigi's repo

Author: Eric Ehlers

ql/exchangerate.hpp

@@ -81,8 +81,7 @@ namespace QuantLib {
 
     // inline definitions
 
-    inline ExchangeRate::ExchangeRate()
-    : rate_(Null<Decimal>()) {}
+    inline ExchangeRate::ExchangeRate() : rate_(Null<Decimal>()), type_(Direct) {}
 
     inline ExchangeRate::ExchangeRate(Currency source, Currency target, Decimal rate)
     : source_(std::move(source)), target_(std::move(target)), rate_(rate), type_(Direct) {}