Fixes necessaries for compile dfly with clang

[Juan Francisco Cantero Hurtado <iam@xxxxxxxxxxxx>]

In the last weeks I've tried compile dfly with clang (with the help of
swildner@). The most of C code compile with clang but the big problem
now is lib/citrus and related code. It doesn't compile and the fix isn't
simple. I'm not a C programmer, so I've written this mail for people
interested in take this task.

DragonFly, FreeBSD and NetBSD has very similar versions of citrus.
OpenBSD took a different and simpler aproach. I suggest for interested
people, look in the FreeBSD code because they is working with clang and
will be more easy discard possible bugs.

Don't use clang from pkgsrc, 3.0 is coming soon and trying with 2.9 is a
waste of time. Install clang by hand is very easy but if you have
problems, ask me.

Other problem is the C++ code (e.g. binutils doesn't compile) but I
consider most important now only the problems related to C.

If you want work in this, install clang, add "CCVER=clangsvn" to
/etc/make.conf and compile the system with buildworld. You also will
need this patches or wait a few days for obtain the code patched from
the git repo:
http://bugs.dragonflybsd.org/issues/2205 ,
http://bugs.dragonflybsd.org/issues/2206 ,
http://bugs.dragonflybsd.org/issues/2207 .

Cheers.

-- 
Juan Francisco Cantero Hurtado http://juanfra.info