[Vala] Defininig _GNU_SOURCE...

[Marco Trevisan (Treviño) <mail 3v1n0 net>]

Hello, I'm writing a small VAPI file for a GNU hader that requires to be
included as:

        #define _GNU_SOURCE
        #include <header_file.h>

Of course I can't do it nor in vala or vapi files, but to compile the
code I have (avoiding the linker errors) I need to define _GNU_SOURCE...

A solution is running valac as:

        valac myfile.vala -X -D"_GNU_SOURCE"

but, could be added a better way to perform this? Automatizing such
thing when including a GNU file...