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

[Jean-Marc Lasgouttes]

Le 20/01/2021 à 18:01, Scott Kostyshak a écrit :
> It took me a while to figure out this was going on, but Kornel helped
> fix things for the bundled Hunspell (even for the bundled Hunspell we
> were trying to link against the system Hunspell in CMake). I'm planning
> to search for materials to understand the std::string API. I'm confused
> as to why this only shows up when linking against libhunspell.

Because it is the only external C++ library we use that uses std::string 
in its interface. The implementations differ too much between the two 
libraries to be compatible in memory, so it is nice that kinking fails.

JMarc