[PATCH] quiesce clang warnings for opie/libopie

Spent some time investigating warnings emitted by the build for libopie
and such.

http://people.freebsd.org/~sbruno/libopie_warns.txt

Most of this is harmless and clang emits clear directives and solutions
to solve these warnings.  Patch attached to do just that and make the
build happy.

http://people.freebsd.org/~sbruno/libopie_clang_warnings.txt

From my eye, it appears that opie should be tracking some other project
or something?  

sean