Partial fixes for OS X

[wxsBSD]

I've done some minor work to get libuinet to build under OS X again. It's not complete and I'm not particularly happy with how I turned off netmap, but libuinet does compile cleanly with these changes:

https://github.com/wxsBSD/libuinet/commit/0623d029b495f7656898592d1e5b0b203d2a910e

However, when building anything that uses libuinet fails with this:

cc -I/Users/wxs/Documents/dev/libuinet/bin/echo/../../lib/libev -g -O0  -I/Users/wxs/Documents/dev/libuinet/bin/echo/../../lib/libuinet/api_include  -o echo echo.o  -L/Users/wxs/Documents/dev/libuinet/bin/echo/../../lib/libuinet -luinet /Users/wxs/Documents/dev/libuinet/bin/echo/../../lib/libev/.libs/libev.a -lm -lpcap -lpthread -lssl
Undefined symbols for architecture x86_64:
  "__DYNAMIC", referenced from:
      _link_elf_init in libuinet.a(libuinet.ro)
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
make: *** [echo] Error 1

If you are interested in the changes mentioned above I'd be happy to submit them as a pull request or if you can point me in the right direction for solving this I'd be happy to come back if I can get any further with it.