Debugger: Pass Abi as const reference

Change-Id: I9f7ef9becc1509cea9ee8f9284a09fc10fdb150f
Reviewed-by: hjk <hjk121@nokiamail.com>

src/plugins/debugger/gdb/gdbengine.cpp

@@ -1463,7 +1463,7 @@ void GdbEngine::handleStopResponse(const GdbMi &data)
         handleStop1(data);
 }
 
-static QByteArray stopSignal(Abi abi)
+static QByteArray stopSignal(const Abi &abi)
 {
     return (abi.os() == Abi::WindowsOS) ? QByteArray("SIGTRAP") : QByteArray("SIGINT");
 }