warn_unused_result problem, and a solution

Hi,

when I updated one of my Ubuntu machine's packages, it automatically 
updated libc6 to a newer version.

I was in for a surprise: the output is littered with spurious warnings 
about lack of handling of return values to all kinds of functions.

It took me a while to figure out what had happened, and it took me even 
longer to find this:

	https://bugs.launchpad.net/ubuntu/+source/glibc/+bug/305176

Apparently, the good Ubuntu people think it is fine that people who 
compile stuff themselves are drowned in warnings.

To make a long story less long: I have this in my config.mak for now:

	CFLAGS += -U_FORTIFY_SOURCE

Hopefully, this helps others, too.

Ciao,
Dscho