do not strip, compile with debugging symbols

[xorquewasp at googlemail.com]

Hello.

What's the correct way to ensure that ports are built with '-g'
and that binaries/libraries created are not stripped? I'm assuming
the first one involves setting CFLAGS in /etc/make.conf (admittedly,
it's apparently not supported but I'm not building world with this
setting anyway).

The second, I'm not so sure about. I thought I'd heard of a NO_STRIP
setting but if it exists, it's not documented.

xw