Guidelines for new base code and sub-project for the rest

[Joerg Sonnenberger]

Hi all,
from recent userland commits of mine, you should be aware of the
WARNS=6 comments. Adding
WARNS?=	6
to a Makefile adds a _lot_ of compiler warning flags, some of them
important, some of them bogus. Included are more important ones like
us of initialized variables and cast-away of const or volatile and
esp. evil the initialisation with string constants.

If you want to add new code into base (not src/sys, different rules
apply there), please ensure that it is WARNS=2 clean and try to make
it WARNS=6 clean. If it is coming from outside, e.g. another BSD
splitting the important and warning clean patch into two parts is
OK, esp. if you can't commit it yourself :)

It's my hope that we can have a WARNS=6 default for all the BSD code
outside src/contrib in the long term and maybe even use -Werror by
default.

Joerg