[LyX/master] Add move constructor and move assignment operator for FileName class

[Stephan Witt]

Am 13.01.2021 um 10:21 schrieb Yuriy Skalko <yuriy.skalko at gmail.com>:
> 
>> Hi Yuriy,
>> I’m seeing a crash after this commit when using File->Open recent.
>> I’m having 5 files in list and the first entry has nullptr as private data.
> 
> Hi Stephan,
> Sorry for late answer. Does it crash always on choosing the first file in Recent list? I cannot reproduce this on Windows and Linux (using GCC in both cases) and suspect it is Clang-only issue.

Yes, perhaps it is a clang issue. Yes, it crashes always. No matter if I use the first or another entry of the five last used files.

Stephan

> 
> As I understand Scott used Clang on Linux. Is this crash reproducible there?
> 
> 
> Yuriy