[LyX/master] Do not return copies of string members

[Jean-Marc Lasgouttes]

Le 11/05/2023 à 19:59, Enrico Forestieri a écrit :
>> Is this somthing special about cygwin or is our autoconf test broken?
> 
> The former, I think. This is what I get when comparing cygwin and native 
> windows configuration:
> 
> $ diff -up build-cygwin/config.h build-win32/config.h | grep -B1 STD_STRING
>   /* std::string uses copy-on-write */
> -#define STD_STRING_USES_COW 1
> +/* #undef STD_STRING_USES_COW */
> 
> So, cygwin is using COW in the std::string implementation...

Or our test is broken on cywin... I think the new thread-safe string 
type is required for C++11 compliance.

JMarc