[PATCH setxkbmap] Eliminate limitations on path length.

[Van de Bugger]

Thanks for the suggestion, I did not know about asprintf. I thought it was my invention. ;-)

Of course, I would like to use asprintf. But rprintf is still required to check the status returned by asprintf.

I am not sure how to define _GNU_SOURCE macro. I done it with #define in the source. 

Ok, here is the attempt #2: