Merge pull request #157 from tedu/master

very basic openbsd support
fix scm rockspec for openbsd
fix openbsd clock_t
add stub openbsd tests
add initial openbsd ctest
openbsd ctest fixes
openbsd constant fixes
openbsd constant fixes
openbsd constant fixes
openbsd constant fixes
openbsd constant fixes
openbsd ioctl fixes
openbsd ioctl fixes
openbsd ioctl fixes
openbsd constant fixes
openbsd constant fixes
openbsd constant fixes
openbsd constant fixes
openbsd constant fixes
openbsd constant fixes