followup to Debian report #68448

[Matthias Klose <doko@cs.tu-berlin.de>]

See http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=68448&repeatmerged=yes

Compiling with gcc -Wall -Werror shows the very same error as with
g++. You can compile with -D_GNU_SOURCE to get the declaration from
stdio.h.