[Translation-i18n] How to translate a string in file scope.

[Lyre <41...@gm...>]

for example, i have a string in file scope:

char *str = "hello world";

int main ()
{
...
}

And for some reasons I could not put the string in a function. Is there a
way to translate it? Typping ' char *str = _("hello world");' outside of
functions would not  work.

BTW, I noticed virsh in libvirt is able to translate strings in file scope,
and their implement looks like this:

#define N_(str) str

char *str = N_("just an example");

But I'm not able to trace how they did it.