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

[Yuriy Skalko]

> Yes, it helps. Now the next are
>         /usr2/src/lyx/lyx-git/src/graphics/GraphicsCacheItem.cpp:445
>         /usr2/src/lyx/lyx-git/src/mathed/MathExtern.cpp:602
>         /usr2/src/lyx/lyx-git/src/mathed/MathExtern.cpp:687
>         /usr2/src/lyx/lyx-git/src/mathed/MathExtern.cpp:772
>         /usr2/src/lyx/lyx-git/src/mathed/MathExtern.cpp:860
>         /usr2/src/lyx/lyx-git/src/Buffer.cpp:1474
>         /usr2/src/lyx/lyx-git/src/BufferList.cpp:131
>         /usr2/src/lyx/lyx-git/src/TocBackend.cpp:148
> 
> Changing all of them now compiles. Thanks.
> 
>         Kornel


Great. So Clang is more strict than GCC. But why Stephan and Scott don't 
have these errors with it? Do you have some additional compiler flags 
active?


Yuriy