#331 Compile warnings on FreeBSD 10.0 using Clang

[Utkonos]

While compiling libevent 2.0.21 on FreeBSD 10.0 there are a number of unused function warnings. I looked at one, and it seems to be declared in the header, but only used for tests.

FreeBSD now uses Clang to compile, BTW. Here are the warnings (I removed extraneous info).
http://paste.kde.org/pjk5ujkwp